Clean-up, Fixes and new Datagen content

[JR1811]

Fixes

• fixed a lot of outdated asset namespaces (mod_id → referencemod)
• missing code in build.gradle which caused minecraft not to consider generated assets as actual game assets
• LoggerUtil was missing some return statements, which caused additional errors in the console
• events all were executed by the common entrypoint (relocated some render events to the client entrypoint)

Content

For a potential BlockState datagen page #33 , new content has been added. It contains:

• new Block (AdvancedTestBlock)
• custom BlockState properties (MyModProperties)
• new datagen class (MyModelProvider)
  • implements all BlockStates of the AdvancedTestBlock and also adds horizontal rotation values
  • adds new model for the AdvancedTestBlock item

The page itself hasn't been written yet, and if this stuff is not needed, it can be deleted again.

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Sorry for not clearly splitting the fixes from the content... 😅

[IMB11]

All good! Just make sure you make a PR later with the page 👍