Change how invisible patterns represented in haskell syntax and TH AST (#24557)

Before this patch:
  data ArgPat p
    = InvisPat (LHsType p)
    | VisPat (LPat p)

With this patch:
  data Pat p
    = ...
    | InvisPat (LHsType p)
    ...

And the same transformation in the TH land. The rest of the
changes is just updating code to handle new AST and writing tests
to check if it is possible to create invalid states using TH.

Metric Increase:
    MultiLayerModulesTH_OneShot