[clang-format] distinguish function type casts after 21c18d5a

https://github.com/llvm/llvm-project/commit/21c18d5a04316891110cecc2bf37ce51533decba
improved the detection of multiplication in function call argument lists,
but unintentionally regressed the handling of function type casts (there
were no tests covering those).
This patch improves the detection of function type casts and adds a few tests.

Reviewed By: HazardyKnusperkeks

Differential Revision: https://reviews.llvm.org/D104209