[ARM][FPEnv] Lowering of fpmode intrinsics (#74054)

LLVM intrinsics `get_fpmode`, `set_fpmode` and `reset_fpmode` operate
control modes, the bits of FP environment that affect FP operations. On
ARM these bits are in FPSCR together with the status bits. The
implementation of these intrinsics produces code close to that of
functions `fegetmode` and `fesetmode` from GLIBC.

Pull request: https://github.com/llvm/llvm-project/pull/74054