EPA: Move EpAnn out of extension points
Use a tuple in the extension field for GhcPs for token locations, and keep the EpAnn field in the surrounding XRec.
Leaving a few that are too tricky, maybe some other time.
Also
- remove some unneeded helpers from Parser.y
- reduce allocations with strictness annotations
Addresses #23447
Edited by Vladislav Zavialov