Refactor contributing guide

[timneutkens]

Splits contributing guide into a directory with multiple files that are linked from the main contributing.md file.

• Added additional details on linting.
• Added explanation of stable vs canary channel and how to publish them for maintainers.
• Added explanation on how a version is decided.
• Changed recommendation for fork workflow to use GitHub CLI instead.
• Changed testing recommendation to always be headless + narrow down the run. Changed command to pnpm test to simplify.
• Added "why" and "the fix" for pnpm new-error, also added logging of the error url at the end of the command.

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running pnpm lint
• The examples guidelines are followed from our contributing doc

[balazsorban44]

Closing in favor of #40515. All comments will be addressed there. Will mark it as ready for review when it is ready. 🙏