Clean up some edge cases in plpgsql's %TYPE parsing.
Support referencing a composite-type variable in %TYPE.
Remove the undocumented, untested, and pretty useless ability
to have the subject of %TYPE be an (unqualified) type name.
You get the same result by just not writing %TYPE.
Add or adjust some test cases to improve code coverage here.
Discussion: https://postgr.es/m/716852.
1704402127@sss.pgh.pa.us