GNU and Apple `strip` implementations seems to support grouped options.
Enable the support for grouped options introduced in
https://reviews.llvm.org/D83639 for `llvm-strip` invocations.
Includes test that checks that both the grouped and non grouped
invocations produces the same result.
Reviewed By: alexander-shaposhnikov, MaskRay
Differential Revision: https://reviews.llvm.org/D105249
Daniel Rodríguez Troitiño