clang-tidy Support

[dsanders11]

Support will fall out automatically from #26, but clangd reads the on-disk configuration for clang-tidy, or lets you change clang-tidy config in the clangd config file. However, it's useful to allow running one-off clang-tidy checks without requiring modifying configs. Add an "Electron Build Tools: Run clang-tidy" command which will provide a quick pick to select checks to run (populate from clang-tidy --checks=* --list-checks) and whether or not to automatically fix the errors (clang-tidy --fix).