Fixups: regression tests

Don't enforce RLS on RI constraints

Plan cache invalidation support for rowsecurity

More recursion tests

More recursion tests

RLS: Initial demo of rewriter based row security

lacks recursion detection (but that looks easy now), plan invalidation so far

Still needs proper COPY (not just ERROR)

RLS: Regression tests

RLS: Detect infinite recursion and abort

(against upd.s.b. views) Updatable s.b. views code needs to adjust ro…

…wmarks

This oversight was not triggered when using security barrier views directly,
because only security barrier views that were DML targets were collapsed into
securityQuals, and special RowMark handling was already in place for these
during rewriting.

RLS: Enforce row-security constraints

Row-security constraints are enforced here by having the securityQual expansion
code check for a row-security constraint before expanding quals.