Pmc: Better SCC annotations and trace output
While investigating #20106, I made a few refactorings to the pattern-match checker that I don't want to lose. Here are the changes:
- Some key functions of the checker now have SCC annotations
- Better
-ddump-ec-trace
diagnostics for easier debugging. I added 'traceWhenFailPm' to see why a particularMaybeT
computation fails and made use of it ininstCon
.