[clang] [libclang/python] Refactor enum usage (PR #95608)

[Jannick Kremer via cfe-commits]

DeinAlptraum wrote:

@Endilll can I ask you for a review again?
As a next step towards the python-bindings strict typing PR, this one captures all the enum refactoring changes necessary towards that goal. Don't be scared by the LoC changed: 90% of that is just indentation changes :)

https://github.com/llvm/llvm-project/pull/95608