STCC-220 Implement/Refactor Userbricks [TN]

[TauBossss]

Implemented and Refactored Userbricks. The implementation changed completely, so i could not use a lot of old code. There is one problem with testing, there is no brickfield for the InputFormulaField, so i couldn't figure out how to test it in the test_converter.py and i looks like it is also missing in the catrobat code. Thats why the lines for testing the formula field are commented out.

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