Fabric extension API, v3

[Sturmlilie]

Continuation of #115.

Changelog:

• LocalAPI -> API (with no Client / Common distiction, for convencience)
• Move font type enum into FontRenderAPI
• Move FontRendererAPIImpl to client package
• Split ManualAPI into Client/Common parts
• Mark BundledRedstoneAPI as experimental

I'm currently having some issues with the serial interface for the brewing stand in my sample extension mod, but I don't think it's related to these changes. If you find the changes here to be fine, please hold off on merging until I fix the mentioned issue though, just to be sure. Thanks :)

Edit: Turns out the issue with the serial interface comes down to something unrelated to the API.

[fnuecke]

Thanks again so much for your work on this :)