Introduce clang rulefile for united style

Frederik Alexander Keensrequested to merge
Style-format into main

Added a clang-format rulefile that defines the codestyle of our project according to the styleguide from moodle.
Also formatted current main with this rulefile.
VSCode should pick this style up when formatting with alt + shift + f,
if not please format with clang-format -i <files> in the future before pushing.
(You need to install clang-format with at least V.14)

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