pgsql: Fix ruleutils.c's dumping of whole-row Vars in more contexts.

Fix ruleutils.c's dumping of whole-row Vars in more contexts.

Commit 7745bc352 intended to ensure that whole-row Vars would be
printed with "::type" decoration in all contexts where plain
"var.*" notation would result in star-expansion, notably in
ROW() and VALUES() constructs. However, it missed the case of
INSERT with a single-row VALUES, as reported by Timur Khanjanov.

Nosing around ruleutils.c, I found a second oversight: the
code for RowCompareExpr generates ROW() notation without benefit
of an actual RowExpr, and naturally it wasn't in sync :-(.
(The code for FieldStore also does this, but we don't expect that
to generate strictly parsable SQL anyway, so I left it alone.)

Back-patch to all supported branches.

Discussion: https://postgr.es/m/efaba6f9-4190-56be-8ff2-7a1674f9194f@intrans.baku.az

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/43c2175121c829c8591fc5117b725f1f22bfb670

Modified Files
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src/backend/utils/adt/ruleutils.c | 56 +++++++++++++++++++------------
src/test/regress/expected/create_view.out | 19 ++++++++++-
src/test/regress/sql/create_view.sql | 5 +++
3 files changed, 57 insertions(+), 23 deletions(-)