[TODO] Reimplement //rotate and //flip

[inxomnyaa]

Description:
Due to extracting blockstates into a virion (see #236), the rotate and flip method had to be removed to loosen up the dependency on MWE2.

I have already added API::rotate() in this branch: flip-rotate. As of now it only supports changing the block positions, not the states though.

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TODO list:

• Implement blockstate modifications
• Implement flip
• Correct counterclockwise => clockwise
• Update rotation and flip data json
• Implement rotating around origin/center
• Correct pasting in new chunks not working
• Allow -90 as rotation degrees parameter as synonym for 270
• Fix Rotate- & FlipAction not updating progress / calculating changed count
• Remove unnecessary try-catch blocks
• Allow rotating .mcstructure files