[llvm] Add missing StringExtras.h includes

In preparation for removing the `#include "llvm/ADT/StringExtras.h"`
from the header to source file of `llvm/Support/Error.h`, first add in
all the missing includes that were previously included transitively
through this header.

GitOrigin-RevId: b0abd4893fa1bfae7f71b6b6e98770c9b1c07620
1 file changed