[Meta-branch] Karma -> WTR migration and Grunt removal

[matux]

Description of the change

This branch consolidates the following approved PRs:

• Initial Karma to Web Test Runner migration #1289
• Fix hanging tests and expand WTR migration #1295
• Migrate example tests for Web Test Runner #1298
• Migrate browser transform and core tests for Web Test Runner  #1299
• Migrate browser tests from Karma to Web Test Runner #1300
• Initial migration of react native tests #1301
• Remove Grunt and Karma #1302

SDK-493/replace-karma-with-webtest-runner-for-modern-performant-browser

[Copilot]

Pull Request Overview

This PR migrates the project from Karma test runner to Web Test Runner (WTR) with Playwright and removes Grunt as a build tool. The migration modernizes the testing infrastructure for better performance and maintainability while maintaining test functionality.

• Migration from Karma to Web Test Runner with Playwright for browser testing
• Replacement of Grunt build system with npm scripts
• Update of test assertion syntax from Chai 4 to Chai 5 style

Reviewed Changes

Copilot reviewed 58 out of 59 changed files in this pull request and generated 11 comments.

Show a summary per file

File	Description
web-test-runner.config.mjs	New WTR configuration with Playwright launcher and test framework settings
package.json	Removed Karma/Grunt dependencies, added WTR packages, updated npm scripts
test/**/*.test.js	Updated test files with ES6 imports and Chai 5 assertion syntax
test/util/*.js	New utility modules for timers and fixture loading in WTR environment
karma.conf.cjs	Removed Karma configuration file
Gruntfile.cjs	Removed Grunt build configuration

Comments suppressed due to low confidence (1)

test/browser.rollbar.test.js:1

• The test expects an array to be converted to an object with numeric keys, but the test description and variable name suggest it should remain an array. This inconsistency could indicate a bug in either the test or the implementation.

import { expect } from 'chai';

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