[slang-tidy] fix slang-tidy's config-file option

[alexeyvoh]

The problem deal with "--config-file" slang-tidy option (file: tools/tidy/src/tidy.cpp line: 76)
The TidyConfigParser constructor have either "std::filesystem::path"(to open file) or "std::string" (for getting config from the string).
The " TidyConfigParser(const std::string& config)" version is selected here in any case instead of "TidyConfigParser(const std::filesystem::path& path)" in case of file exist.
I propose call "TidyConfigParser(std::filesystem::path(tidyConfigFile.value()))" in the file exist case and leave as is other-wise.

[codecov]

Codecov Report

Merging #856 (62ca4c6) into master (52ee547) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #856   +/-   ##
=======================================
  Coverage   93.71%   93.71%           
=======================================
  Files         191      191           
  Lines       46552    46552           
=======================================
  Hits        43626    43626           
  Misses       2926     2926           

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 52ee547...62ca4c6. Read the comment docs.