JS: Tolerate trailing commas in JSON arrays

[asgerf]

Standard JSON does not permit trailing commas, but tsconfig.json files rely on an extension of JSON with trailing commas and comments.

We already extract JSON using this extended format in general, but trailing commas in arrays were not supported, meaning tsconfig.json files were rejected in some cases.

[Copilot]

Pull Request Overview

This PR enables support for trailing commas in JSON arrays for tsconfig.json extraction.

• Added a changenote documenting the fix.
• Removed error-raising logic in JSONParser to allow trailing commas in array literals.
• Updated the extractor version to reflect the changes.

Reviewed Changes

Copilot reviewed 3 out of 5 changed files in this pull request and generated no comments.

File	Description
javascript/ql/src/change-notes/2025-04-10-json-array-trailing-comma.md	Added changenote explaining the fix for trailing commas in array literals in tsconfig.json.
javascript/extractor/src/com/semmle/js/parser/JSONParser.java	Removed the check that raised an error for omitted array elements, thereby allowing trailing commas.
javascript/extractor/src/com/semmle/js/extractor/Main.java	Updated the extractor version to indicate the new release date.

Files not reviewed (2)

• javascript/extractor/tests/json/input/array-trailing-comma.json: Language not supported
• javascript/extractor/tests/json/output/trap/array-trailing-comma.json.trap: Language not supported