[flang] Add -f[no-]honor-infinities and -menable-no-infs

Only add the option processing and store the result. No attributes are
added to FIR yet.

This patch follows Clang in forwarding -fno-honor-infinities as
-menable-no-infs.

Reviewed By: kiranchandramohan awarzynski vzakhari

Differential Revision: https://reviews.llvm.org/D137072