[clang-tidy] Make readability-container-size-empty check using <string> header

Improve the generic <string> header by adding the size() method so that
it can be used to replace the custom implementation in the
readability-container-size-empty check.

This requires fixing an incorrect comparison of a std::wstring with a
char string literal.

Unfortunately, removing the custom basic_string implementation means
fixing the line numbers for many of the checks.

Depends on D145312

Reviewed By: PiotrZSL

Differential Revision: https://reviews.llvm.org/D145313