rafactor: Migrate karma config files to ts and fix types in browser-test-runner

[mondoreale]

This pull request migrates Karma and Webpack configuration files from CommonJS/JavaScript to ES Modules/TypeScript across several packages, and improves type safety and maintainability for browser-based tests. It also refactors the createKarmaConfig and createWebpackConfig APIs to use proper Webpack types, updates custom matcher imports, and adjusts package scripts to use the new TypeScript config files.

Changes

Configuration migration and refactoring:

• Migrated all Karma and Webpack config files in dht, proto-rpc, sdk, and trackerless-network packages from .js/CommonJS to .ts/ES Modules, updating imports and exports accordingly.
• Refactored createKarmaConfig and createWebpackConfig in browser-test-runner to use proper Webpack types (Configuration, ExternalItem, etc.), improving type safety and merging external dependencies more robustly.

Test setup improvements:

• Updated custom matcher imports in karma-setup.js files to use ES Module syntax (import instead of require) for consistency and compatibility.

Package script updates:

• Updated test-browser and related scripts in package.json files to use .ts config files instead of .js, ensuring the new TypeScript-based configs are used for browser tests.

File renaming and cleanup:

• Removed obsolete .js config files and replaced them with .ts equivalents where appropriate, cleaning up the codebase and reducing duplication.

Webpack configuration enhancements:

• Added explicit empty alias and fallback fields to resolve in webpack.config.js to support new type definitions and ensure compatibility with the updated config factories.

[teogeb]

Good improvement 👍

[teogeb]

Can we avoid this casting?

[mondoreale]

Yeah, by… casting the result of defaultConfig but it makes merging them configs a mess.

[mondoreale]

Well, that's actually a "no", eh?