Refactor translation unit glob pattern to handle large directories

[bkryza]

Currently, when -u dir/**/*.cpp is specified on a very large directory, the time to filter the translation units against the compile commands is very long. This should be refactored, so that first we extract the files from compile commands and then check them against the glob pattern instead of listing everything.

[LuridHound]

@bkryza , I am currently working on PR for this issue. Are you working on it at the moment?

I wouldn't like to duplicate the work

[bkryza]

@LuridHound Thanks for heads up, I'm not working on it right now.