draft: feat: first commit to split types and core functionalities

[gitaarwerk]

This is the first draft to move towards splitting the repository for multiple platforms.

For now focus is to move all sharable core to core package (local only). Split types to a separate package as well so devs can include it themselves whenever they feel like it. Typescript may or may not be available in the types package @types later on.

One big change is moving organisatory repository

Publishable packages:

• @gleamy/react (the current package as we know it)
• @gleamy/types (the types for all (future) packages)

Internal packages:

• @gleamy/dev-environment (the development environment to test-drive all changes using NextJS)
• @gleamy/core (core shareable functions)