Error message with EmptyCase and RequiredTypeArguments (#25004)

Fix a panic triggered by a combination of \case{} and forall t ->

  ghci> let f :: forall (xs :: Type) -> (); f = \case {}
  panic! (the 'impossible' happened)
    GHC version 9.10.1:
          Util: only

The new error message looks like this:

  ghci> let f :: forall (xs :: Type) -> (); f = \case {}
  <interactive>:5:41: error: [GHC-48010]
      • Empty list of alternatives in \case expression
        checked against a forall-type: forall xs -> ...

This is achieved as follows:

* A new data type, BadEmptyCaseReason, is now used to describe
  why an empty case has been rejected. Used in TcRnEmptyCase.

* HsMatchContextRn is passed to tcMatches, so that the type checker
  can attach the syntactic context to the error message.

* tcMatches now rejects type arguments if the list of alternatives is
  empty. This is what fixes the bug.