Refactor!: Make package using modules and type only

[susnux]

• Alternative / closes fix: Remove js file from dist and use only provide Typescript definitions #242

Brace yourself the diff is huge!
This is a complete refactor of the library and contains this changes:

1. (breaking!) Make the package use modules instead of namespaces, this is the recommended way since ES modules are part of the language. This also fixes some weird behavior of referencing types with Typescript 5.5. Moreover this allows to separate the code better and reuse parts that we use later (probably) for new versions.
2. Consolidate all types into Nextcloud28 as this is the oldest supported version. This allows to cleanup the code a bit.
3. Add NextcloudLatest alias type export
4. Use ESLint for code linting
5. Use Prettier to enforce consistent code style
6. Add SPDX headers and make package REUSE compliant

[AndyScherzinger]

Add SPDX headers and make package REUSE compliant

Already on master @susnux - you might want to rebase

[susnux]

@AndyScherzinger thank you, done :)

[AndyScherzinger]

🐘

[susnux]

Still WIP - I try to improve UX for developers (but this still works - just try to make it more convinient)