In particular, this allows correct tracking of specified/invisible
for variables in Haskell98 data constructors and in pattern synonyms.
GADT-syntax constructors are harder, and are left until #11721.

This was all inspired by Simon's comments to my fix for #11512,
which this subsumes.

Test case: ghci/scripts/TypeAppData

[skip ci]  (The test case fails because of an unrelated problem
fixed in the next commit.)