Support --learn for inline expectations via learnEdits

`codeql test run --learn` could previously only rewrite `.expected`
files; inline expectations (the `// $ Alert` comments checked by
`InlineExpectationsTest`) had to be fixed by hand. This teaches the
shared test library to compute those source edits so the test runner
can apply them.

The `test-postprocess` query now exposes a `learnEdits` relation
(`file, line, operation, startColumn, endColumn, text`) describing the
minimal source rewrite that would make the inline expectations match the
actual query results. It covers:

  - appending a fresh comment carrying every tag learned for a line that
    has an unexpected result and no existing comment to merge into;
  - rewriting an existing expectation comment as a whole so it matches
    the current results: dropping fixed-spurious tags, promoting a
    `MISSING:` expectation that now fires, clearing a stale `SPURIOUS:`
    annotation, and merging in freshly learned tags, re-rendering the
    remaining expectations (or deleting the comment when none remain);
  - preserving expectations this test does not own -- e.g. a tag
    annotated with a different query's id that shares the source file --
    and any trailing regular note (`// $ Alert // note`);
  - recording any unexpected result, not just `Alert`.

Edits are emitted as a query predicate rather than applied here: the
engine consumes `learnEdits` only under `--learn` and ignores it
otherwise, so ordinary `test run` output is unchanged.

Comment syntax is provided per language by each
`InlineExpectationsTestQuery.ql`'s `Input` (`getStartCommentMarker`),
which for now renders only line-comment languages; block-comment
languages (XML/YAML) can supply their markers later without changing
this relation's shape.

Author: d10c

cpp/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,13 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // C/C++ databases can also contain XML (e.g. `.xml`, `.props`), whose block-comment
+    // syntax is not yet supported, so we only render for C/C++ sources.
+    relativePath
+        .regexpMatch(".*\\.(c|cc|cpp|cxx|cp|c\\+\\+|h|hh|hpp|hxx|h\\+\\+|inl|tcc|ipp|tpp|cu|cuh)") and
+    result = "//"
+  }
 }

csharp/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // C# databases can also contain XML (e.g. `.csproj`, `.config`) and Razor markup, whose
+    // comment syntaxes are not yet supported, so we only render for C# sources.
+    relativePath.regexpMatch(".*\\.(cs|csx)") and
+    result = "//"
+  }
 }

go/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // Go databases can also contain XML, whose block-comment syntax is not yet supported, so
+    // we only render for Go sources.
+    relativePath.matches("%.go") and
+    result = "//"
+  }
 }

java/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // Java databases can also contain XML; those files use a different (block) comment
+    // syntax that is not yet supported, so we only render for Java and Kotlin sources.
+    (relativePath.matches("%.java") or relativePath.matches("%.kt")) and
+    result = "//"
+  }
 }

javascript/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // JavaScript databases can also contain HTML, whose (block) comment syntax is not yet
+    // supported, so we only render for the line-comment source files.
+    relativePath.regexpMatch(".*\\.(js|cjs|mjs|jsx|ts|cts|mts|tsx)") and
+    result = "//"
+  }
 }

python/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // Python databases can also contain XML, whose block-comment syntax is not yet supported,
+    // so we only render for Python sources.
+    relativePath.regexpMatch(".*\\.(py|pyi)") and
+    result = "#"
+  }
 }

ql/ql/src/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // The QL extractor can also extract YAML (e.g. `qlpack.yml`), whose `#` comment syntax
+    // differs, so we only render for QL sources and dbscheme files.
+    relativePath.regexpMatch(".*\\.(ql|qll|dbscheme)") and
+    result = "//"
+  }
 }

ruby/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // Ruby databases can also contain ERB, whose comment syntax is not yet supported, so we
+    // only render for plain Ruby sources.
+    relativePath.matches("%.rb") and
+    result = "#"
+  }
 }

rust/ql/lib/utils/test/InlineExpectationsTestQuery.ql

@@ -18,4 +18,12 @@ private module Input implements T::TestPostProcessing::InputSig<Impl> {
         f.getRelativePath() + ":" + startline + ":" + startcolumn + ":" + endline + ":" + endcolumn
     )
   }
+
+  bindingset[relativePath]
+  string getStartCommentMarker(string relativePath) {
+    // Rust databases can also contain YAML, whose `#` comment syntax differs, so we only
+    // render for Rust sources.
+    relativePath.matches("%.rs") and
+    result = "//"
+  }
 }