chore: use test context for webidl tests

[Uzlopak]

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[Copilot]

Pull Request Overview

This PR refactors webidl test files to use the test context (t) parameter instead of directly importing and using the assert module. This modernizes the test structure to follow Node.js test runner conventions.

Key Changes

• Remove direct assert module imports from all test files
• Update test function signatures to accept the test context parameter (t)
• Replace assert.* calls with t.assert.* calls throughout the test suite

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
test/webidl/util.js	Refactors test functions to use test context for assertions
test/webidl/helpers.js	Updates interface and dictionary converter tests to use test context
test/webidl/errors.js	Modernizes error handling tests with test context
test/webidl/converters.js	Converts all converter tests to use test context pattern

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