feat(*): migrate to nx monorepo

[thompsonsj]

Migrate to an NX integrated repo.

The current workspace based approach causes a number of issues which are resolved by migrating to a monorepo. Example issues:

• There are a lot of imports in the Payload test installation from dist folders.
• React components are hard to work with due to https://legacy.reactjs.org/warnings/invalid-hook-call-warning.html.
• TypeScript/Linting are not configured in an ideal way. Move this responsibility to NX, which configures environments out of the box.

Some notes on this change:

• Helpful advice on configuring Payload CMS in a monorepo: feat(payload): migrate to nx monorepo and add payload test install payload-plugin-sso#2.
• Includes a major refactor of code to meet new lint/TypeScript requirements.
• Uses the test installation types - some typing is added for collection/global slugs. Keep an eye on this - will this affect the distribution?