Initial implementation of Zc * sequencer

Created by: silabs-oysteink

Ported sequencer from cv32e41p PR 24.

• Updated from spec 0.5 to 0.70.4

All sequences for PUSH, POP* and double moves are in.

Missing:

• Proper handling of exceptions
• Not detecting all illegal encoding for sequenced instructions
• Not propagating 'last_op' properly (not propagating last_op made it easier to verify sequences using rvfi logs during simulation)
• Interaction with interrupts and debug.

SEC clean when ZC_EXT=0