Blender Git Loki

macOS deps: Support building clang tidy

This patch builds clang-extra-tools on macOS for the
clang-tidy binary. The script "run-clang-tidy.py" is
also harvested because using the `CMAKE_C[XX]_CLANG_TIDY`
option can miss out some files (like makesrna), and using the
script is faster as it does not compile the files.
Thanks to `@LazyDodo` for the base patch D8502.

Reviewed By: LazyDodo, sebbas, #platform_macos
Differential Revision: https://developer.blender.org/D9450