Run the renamed source plugin after each HsGroup
This allows modification of each HsGroup after it has been renamed.
The old behaviour of keeping the renamed source until later can be
recovered if desired by using the keepRenamedSource plugin but it
shouldn't really be necessary as it can be inspected in the TcGblEnv.
Reviewers: nboldi, bgamari, alpmestan
Reviewed By: nboldi, alpmestan
Subscribers: alpmestan, rwbarton, thomie, carter
GHC Trac Issues: Trac #15315
Differential Revision: https://phabricator.haskell.org/D4947