add Intel OneApi compiler to CI

Changes done to CMake:

• Disable MemoryUsage test for intel LLVM. Apparently, the intel compiler allocates more memory than needed. But as far as I know, there are no "rules" or standards on how much memory will be allocated with a std::vector
• Add a check if "the OpenMP sign conversion bug" (https://bugs.llvm.org/show_bug.cgi?id=48387) exists and disable the corresponding warning
• add WALBERLA_BUILD_WITH_INTELLLVM variable
• disable Fast Math if it is not explicitly turned on. Otherwise, it would be enabled with O1 and above

Depends on https://i10git.cs.fau.de/walberla/buildenvs/-/merge_requests/32