CI: Add Control Flow Integrity sanitizer

[chfast]

Add CI job with Control Flow Integrity sanitizer in Clang:

-fsanitize=cfi -fno-sanitize-trap

https://clang.llvm.org/docs/ControlFlowIntegrity.html

[chfast]

I don't think this is super useful (at least at this point), because it protects against misuses of casts we almost don't use, e.g. base to derived class cast, wrong function pointer cast, casts from void*.