By: Tom Sydney Kerckhove <syd@cs-syd.eu>
Apply DisableMutationsFor to BindStmt RHS too
GHC 9.10+ expands @do { p <- e; rest }@ into @(>>=) e (\p -> rest)@ in
the renamer, so the typechecked AST no longer carries a 'BindStmt' the
plugin can match on directly. The original 'BindStmt' is preserved
inside the expansion's 'OrigStmt' field; recognise it there and apply
the 'DisableMutationsFor' scope to the @e@ argument of @(>>=)@ — not to
the continuation lambda, whose body has its own subsequent bind
expansions.