feat: predicates can begin with "."

This commit restricts identifiers to not start with "." and also allows
predicates to be denoted with "." as well as "#", as specified by
`query.c`.

See https://github.com/tree-sitter/tree-sitter/blob/9c8055765849eee39f69a8eda7d2a5aede2b2e60/lib/src/query.c#L2308
and https://github.com/emacs-tree-sitter/tree-sitter-langs/blob/b955ffbe26b3a7e931f116720efa7dee9de35174/queries/hcl/highlights.terraform-mode.scm#L13

Author: ribru17

grammar.js

@@ -10,7 +10,8 @@ const PREC = {
   WILDCARD_NODE: 1,
 };
 
-const IDENTIFIER = /[a-zA-Z0-9.\-_\$]+/;
+// Identifiers cannot start with `.`
+const IDENTIFIER = /[a-zA-Z0-9\-_\$][a-zA-Z0-9.\-_\$]*/;
 
 module.exports = grammar({
   name: "query",
@@ -124,7 +125,7 @@ module.exports = grammar({
     predicate: $ =>
       seq(
         "(",
-        field("name", seq("#", $._immediate_identifier, field("type", $.predicate_type))),
+        field("name", seq(choice("#", "."), $._immediate_identifier, field("type", $.predicate_type))),
         field("parameters", $.parameters),
         ")"
       ),