Allow trailing commas after import attributes in ImportType

[Andarist]

fixes #61916

[Copilot]

Pull Request Overview

This PR enables a trailing comma after the import attributes object in import(...) types and adds tests to verify valid and invalid comma placements.

• Allow an optional comma before closing the import-attributes argument.
• Add new test cases covering no comma, one trailing comma, and double-comma errors.

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

File	Description
tests/cases/conformance/importAttributes10.ts	New tests for import attributes with single and double commas
src/compiler/parser.ts	Insert parseOptional(SyntaxKind.CommaToken) before }

[RyanCavanaugh]

@Andarist I'm going to assign the issue to copilot just for analysis purposes. No shade on this fix, which appears correct (but let's not tell the computer that)