[clang] Add retrieval of unary operator spelling and python bindings (PR #219983)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

Ugh, first it was "server error. try again later", now "merge already in progress".
I'll come back to this later when GitHub is hopefully less broken.

https://github.com/llvm/llvm-project/pull/219983