libafl_ar and libafl_cc automatic configurations mechanism doesn't support response files. #3391
Description
Describe the bug
Modern toolchain components support 'response files', @-prefixed arguments which are names of files including additional command line arguments.
The logic which replaces e.g. xxx.o with xxx.coverage.o in libafl_cc and libafl_ar, when using multiple configurations, does not know about response files, and so projects which use them in their build systems produce incorrect compilation results.
We should refactor the libafl_cc crate to fully support response files.