Consolidate simplification flags

[ailrst]

We currently have three common configurations

1. (default) only the simplifications in doCleanup which we will need to disable when we add a frontend directly from IR
2. --simplify lifting to parameter form DSA / copyprop / branch simplification
3. --simplify --dsa standard --memory-regions dsa --analyse required to enable memory region transform

These could be organised into some aggregate flags like --O0 --O1 --O2 --O3. We likely still want to be able to enable/disable individual passes