[clang] [llvm] [clang][python][test] Move python binding tests to lit framework (PR #145855)

[Rainer Orth via cfe-commits]

rorth wrote:

I'm tired of this constant churn: couldn't you have waited a bit longer?  This is just spare-time work, not a paid job.

https://github.com/llvm/llvm-project/pull/145855