[clang-tidy] Add --use-color command line option and UseColor option to...

[clang-tidy] Add --use-color command line option and UseColor option to control colors in diagnostics

This patch adds `--use-color` command line option and `UseColor` option to clang-tidy to control colors in diagnostics. With these options, users can force colorful output. This is useful when using clang-tidy with parallelization command line tools (like ninja and GNU parallel), as they often pipe clang-tidy's standard output and make the colors disappear.

Reviewed By: njames93

Differential Revision: https://reviews.llvm.org/D79477