Migrate libclang compiled libraries PyPI package to LLVM monorepo

[nightlark]

This is an issue to track the things that need to happen to move the libclang PyPI package into the LLVM monorepo from its current home at https://github.com/sighingnow/libclang

The primary distinction between the libclang and clang packages on PyPI is that libclang supplies pre-compiled copies of libclang for a variety of OS/CPU combinations, and doesn't have a pure Python variant for people on unsupported platforms.

To avoid publishing duplicate bindings under different packaging, I'm thinking we can:

• Keep the clang package as being the pure Python bindings
• Remove the duplicate Python bindings (*.py files) that the libclang package currently bundles, making it native libraries only with clang as a dependency to supply the *.py files

This should make so existing users of each continue to get what they expect, with the libclang package continuing to act as a convenient way for users to get a "batteries included" dependency on most common platforms while consolidating the pure Python binding code into one package.

• Adapt the cibuildwheel setup for building libclang wheels from https://github.com/nightlark/libclang/tree/migrate-to-cibuildwheel to the LLVM monorepo
• Figure out how to best upstream the patches libclang applies to cindex.py in https://github.com/sighingnow/libclang/blob/master/scripts/data/clang_bindings.patch
• @sighingnow transfer ownership of the clang PyPI package to @boomanaiden154 or @tstellar so they can add it to the LLVM PyPI org
• Set up trusted publishing for the libclang PyPI package to use the release-libclang-pypi.yml file in the LLVM monorepo (@tstellar or @boomanaiden154)
• Add a workflow call to the release-libclang-pypi.yml file in release-tasks.yml (this should happen after everything else is set up)

Some discussion about transferring PyPI packages to the LLVM org on PyPI can be found at: https://discourse.llvm.org/t/moving-projects-into-the-llvm-org-on-pypi/88868