YAML: Extract comments

[MathiasVP]

This PR adds support for extraction of YAML comments to all the languages which makes use of the YAML extractor.

To keep this PR simple I've decided to not include the new YamlComment class into the existing Comment classes for each language. I suggest we do that as a per-language follow-up if necessary.

(All the force-pushes is my fumbling with up- and downgrade scripts. The DCA runs should still be representative of the changes)

[Copilot]

Pull request overview

This PR extends the shared YAML extraction model to include YAML comments, adding a new yaml_comments relation/type to the relevant dbschemes and exposing a YamlComment class through the shared YAML QL library and per-language YAML adapters.

Changes:

• Add yaml_comments (and @yaml_comment) to YAML dbscheme fragments and include comments in @yaml_locatable.
• Extend the shared YAML library (codeql.yaml.Yaml) with a comment base type and a YamlComment class.
• Add a JavaScript library test exercising YamlComment.getText().

Show a summary per file

File	Description
unified/ql/lib/unified.dbscheme	Adds yaml_comments and @yaml_comment to the unified YAML schema fragment.
shared/yaml/codeql/yaml/Yaml.qll	Introduces comment support in the shared YAML QL API (CommentBase, YamlComment).
rust/ql/lib/upgrades/77e9a70be4b0cf5ecb1d4c1d841b2d970715a912/upgrade.properties	Declares a Rust db upgrade for YAML comment extraction.
rust/ql/lib/rust.dbscheme	Adds yaml_comments and extends @yaml_locatable for Rust DBs.
rust/downgrades/e1bce498ef78280ebe0a32b1d9d6f26c96eaf41f/upgrade.properties	Declares Rust downgrade behavior for yaml_comments.
ruby/ql/lib/upgrades/29b7b6fc1982422368cb0a4644fd0c81f993c618/upgrade.properties	Declares a Ruby db upgrade for YAML comment extraction.
ruby/ql/lib/ruby.dbscheme	Adds yaml_comments and extends @yaml_locatable for Ruby DBs.
ruby/downgrades/d6f4c73dc33d28aebcffd53ba080eeecc99470f5/upgrade.properties	Declares Ruby downgrade behavior for yaml_comments.
ql/ql/src/ql.dbscheme	Adds yaml_comments and extends @yaml_locatable for QL extractor DBs.
ql/ql/src/codeql_ql/ast/Yaml.qll	Wires YAML comment entities into the QL AST YAML adapter.
ql/ql/src/codeql_ql/ast/Ast.qll	Wires YAML comment entities into the broader QL AST YAML module.
python/ql/lib/upgrades/eb5fc917c79bb23ce2de4a022f3e566d57a91be9/upgrade.properties	Declares a Python db upgrade for YAML comment extraction.
python/ql/lib/semmlecode.python.dbscheme.stats	Updates Python dbscheme stats to include @yaml_comment/yaml_comments.
python/ql/lib/semmlecode.python.dbscheme	Adds yaml_comments and extends @yaml_locatable for Python DBs.
python/ql/lib/semmle/python/Yaml.qll	Wires YAML comment entities into the Python YAML adapter.
python/downgrades/b7745eb2df865c97e50b7803956a82988716e29a/upgrade.properties	Declares Python downgrade behavior for yaml_comments.
python/downgrades/b7745eb2df865c97e50b7803956a82988716e29a/semmlecode.python.dbscheme	Provides the downgraded Python dbscheme variant without yaml_comments.
javascript/ql/test/library-tests/Comments/YamlComments.ql	Adds a JS library test query selecting YamlComment text.
javascript/ql/test/library-tests/Comments/YamlComments.expected	Expected results for the new JS YAML comment test.
javascript/ql/test/library-tests/Comments/comments.yml	YAML fixture used by the JS comment test.
javascript/ql/lib/upgrades/26a123164be893893e2aa0374d820785decf55af/upgrade.properties	Declares a JavaScript db upgrade for YAML comment extraction.
javascript/ql/lib/upgrades/26a123164be893893e2aa0374d820785decf55af/semmlecode.javascript.dbscheme	Upgrade dbscheme snapshot including yaml_comments for JavaScript.
javascript/ql/lib/upgrades/26a123164be893893e2aa0374d820785decf55af/old.dbscheme	Prior JavaScript dbscheme snapshot for the upgrade.
javascript/ql/lib/semmlecode.javascript.dbscheme.stats	Updates JS dbscheme stats to include @yaml_comment/yaml_comments.
javascript/ql/lib/semmlecode.javascript.dbscheme	Adds yaml_comments and extends @yaml_locatable for JS DBs.
javascript/ql/lib/semmle/javascript/YAML.qll	Wires YAML comment entities into the JS YAML adapter.
javascript/extractor/tests/yaml/output/trap/orig.yml.trap	Updates extractor trap output to include extracted YAML comments.
javascript/extractor/tests/yaml/output/trap/emoji_buffer_boundary.yml.trap	Updates extractor trap output to include extracted YAML comments (boundary case).
javascript/downgrades/ce4a5f401c03a70b0595e71bdc20612d82fa4e67/upgrade.properties	Declares JavaScript downgrade behavior for yaml_comments.
javascript/downgrades/ce4a5f401c03a70b0595e71bdc20612d82fa4e67/semmlecode.javascript.dbscheme	Provides the downgraded JS dbscheme variant.
javascript/downgrades/ce4a5f401c03a70b0595e71bdc20612d82fa4e67/old.dbscheme	Current JS dbscheme snapshot used as the downgrade source.
actions/ql/lib/codeql/actions/ast/internal/Yaml.qll	Wires YAML comment entities into the Actions YAML adapter.
actions/ql/lib/codeql/actions/ast/internal/Ast.qll	Exposes YAML comments as Comment in the Actions AST layer.

Copilot's findings

• Files reviewed: 40/44 changed files
• Comments generated: 1