SI-8388 consistently match type trees by originals

Due to the fact that all TypTrees are transformed into TypeTrees
during typechecking one couldn't treat typed type trees in the same
way as they treat untyped type trees.

This change implements support for pattern matching of TypeTrees as their
corresponding TypTree equivalent using tree preserved in the original.

The implementation itself is a trivial wrapping of regular TypTree
extractors into MaybeTypeTreeOriginal.