[clangd][clang-tidy] Remove uses of `std::vector<bool>`

LLVM Programmer’s Manual strongly discourages the use of `std::vector<bool>` and suggests `llvm::BitVector` as a possible replacement.

This patch does just that for clangd and clang-tidy.

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D117119