Added signal aliases the rvfi helper functions

Created by: silabs-mateilga

To help with debugging and waveforms, we have decided that we want signal aliases of the "is_*()" functions of the the rvfi_instr_if. This PR adds those, changes the use in several assertion sets from function to signal, and renames the functions to keep them separate. The _array helper signals have also been fixed, as the previous implementation could cause problems.