[analyzer] FixItHint: Apply and test hints with the Clang-Tidy's script

Summary:
This patch introduces a way to apply the fix-its by the Analyzer:
`-analyzer-config apply-fixits=true`.

The fix-its should be testable, therefore I have copied the well-tested
`check_clang_tidy.py` script. The idea is that the Analyzer's workflow
is different so it would be very difficult to use only one script for
both Tidy and the Analyzer, the script would diverge a lot.
Example test: `// RUN: %check-analyzer-fixit %s %t -analyzer-checker=core`

When the copy-paste happened the original authors were:
@alexfh, @zinovy.nis, @JonasToth, @hokein, @gribozavr, @lebedev.ri

Reviewed By: NoQ, alexfh, zinovy.nis

Differential Revision: https://reviews.llvm.org/D69746