template-haskell: remove Language.Haskell.TH.Lib.Internal

This module is purely used for the implementation of TH quote
desugarring.

Historically this needed to be exposed from `template-haskell`, since
that's the package that the desugarred expressions referenced but since
!12479, this is no
longer the case.

Now these identifiers are in `ghc-internal`.

Note that this module has carried the following warning for a long time:

> This is not a part of the public API, and as such, there are no API guarantees for this
module from version to version.

Resolves #24766