feat!: refactor Admin UX/UI

[justlevine]

What

This PR contains a complete refactor of packages/admin

Todo:

• Add path aliases to tsconfig
• Rename file structure to use kebab-case
• Clean up components/layouts/screen
• Redesign header
• Add custom settings store + REST endpoint
• Refactor settings schema + screens for composability (DRY/SOLID)
• Refactor settings registration
• Settings migration on update

Stretch goals

( These may be punted to a future release ):

• (Breaking) Refactor providers for multitenancy
• (Breaking) Multiple environments ( Support for Multiple Redirect URIs Based on Environment (localhost and production) #140 )
• Add Dashboard Screen
• Linting
• Playwright tests

Why

Unblocks the UX issues + scalability for #129

How

Testing Instructions

Additional Info

Checklist:

• My code is tested to the best of my abilities.
• My code follows the WordPress Coding Standards.
• My code has proper inline documentation.
• I have added unit tests to verify the code works as intended.
• I included the relevant changes in CHANGELOG.md

[coveralls]

coverage: 56.318% (-25.6%) from 81.924%
when pulling c11d845 on feat/refactor-admin
into 72936f4 on develop.