fix a bug affecting ras performance

Added scripts to remove coverage statistics of print and assert.

1. filter out unnecessary coverage statistics
python3 scripts/coverage/coverage.py input.v output.v
2. re calculate the coverage statistics
python3 scripts/coverage/statistics.py output.v

frontend: include icache

Decode: refractor Decode Unit

Frontend refactor on global history

rename: use PipelineConnect instead of DecodeBuffer

Snapshot compress