autocargo/thrift: add support for rust_extra_srcs to fix mononoke OSS cargo build

Summary:
Add support for rust_extra_srcs to autocargo and rust shed thrift wrapper.  Copy extra sources to the cargo thrift build location so that the include!() can find them

Mononoke started using them in D63977688, which is causing [github CI Cargo based builds to fail](https://github.com/facebook/sapling/actions/runs/11329919951/job/31506538796) with `error[E0583]: file not found for module 'extra_thrift'`

Mononoke cargo build was also broken on missing scs_errors and scs_methods crate used from async_requests, hence the autocargo mapping update to include it in following diff D64541433

Reviewed By: andreacampi

Differential Revision: D64541434

fbshipit-source-id: 118508175e4168b15e4c99dd63a6eaa34ac10c5e

Author: ahornby

shed/thrift_compiler/src/lib.rs

@@ -77,6 +77,7 @@ pub struct Config {
     clients_crate: Option<String>,
     options: Option<String>,
     include_srcs: Vec<PathBuf>,
+    extra_srcs: Vec<PathBuf>,
 }
 
 impl Config {
@@ -96,6 +97,7 @@ impl Config {
             clients_crate: None,
             options: None,
             include_srcs: vec![],
+            extra_srcs: vec![],
         })
     }
 
@@ -165,6 +167,13 @@ impl Config {
         self
     }
 
+    /// Set extra srcs to be copied into the generated crate.
+    pub fn extra_srcs(&mut self, value: impl IntoIterator<Item = impl AsRef<Path>>) -> &mut Self {
+        self.extra_srcs
+            .extend(value.into_iter().map(|path| path.as_ref().to_owned()));
+        self
+    }
+
     /// Transform a relative path so leading "../"'s are replaced with "_t".
     pub fn remap_to_out_dir(&self, path: &Path) -> PathBuf {
         let mut rem = path;
@@ -200,6 +209,15 @@ impl Config {
             }
         }
 
+        for extra_src in &self.extra_srcs {
+            println!("cargo:rerun-if-changed={}", extra_src.to_string_lossy());
+            if let GenContext::Types = self.gen_context {
+                let out_path = self.remap_to_out_dir(extra_src);
+                fs::create_dir_all(out.join(out_path.parent().unwrap()))?;
+                fs::copy(extra_src, out.join(out_path))?;
+            }
+        }
+
         if let [(_name, file)] = &input[..] {
             match self.gen_context {
                 GenContext::Types => {