Term variable capture (#23740)

This patch changes type variable lookup rules (lookupTypeOccRn) and
implicit quantification rules (filterInScope) so that variables bound
in the term namespace can be captured at the type level

  {-# LANGUAGE RequiredTypeArguments #-}
  f1 x = g1 @x                -- `x` used in a type application
  f2 x = g2 (undefined :: x)  -- `x` used in a type annotation
  f3 x = g3 (type x)          -- `x` used in an embedded type
  f4 x = ...
    where g4 :: x -> x        -- `x` used in a type signature
          g4 = ...

This change alone does not allow us to accept examples shown above,
but at least it gets them past the renamer.