Rewrite data-family R: TyCons to abstract family applications

Rewrite data-family R: TyCons to abstract family applications

GHC represents `data instance Foo Args = …` internally as a
synthetic TyCon `R:FooArgs`. When such a TyCon shows up inside a
constraint or instance head — `NoThunks (R:ConsensusConfigPraos c)`
— the user reads it as the abstract family application
`NoThunks (ConsensusConfig (Praos c))`. Until now we faithfully
reported the rep TyCon, which surfaced the synthetic name.

In typeArg, gate on tyConFamInst_maybe before the regular TyConApp
path: when the TyCon is a data-family instance representation,
emit `FamilyApp parent parentArgs` instead. The viewer's existing
chain logic then naturally connects the @data instance@ row to any
class instance that mentions the abstract family.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>