[clang] [libclang/python] Add `Cursor.from_translation_unit` (PR #140496)

[Jannick Kremer via cfe-commits]

https://github.com/DeinAlptraum approved this pull request.

LGTM, but are you sure there is a need for this API? This just seems like a slighly less convenient version of `TranslationUnit.cursor`.

> This should complete the list of things Cursor can be made from.

There is also a `cursor` property on `Token`s

https://github.com/llvm/llvm-project/pull/140496