pgsql: pg_visibility: Restrict access to more relation types

pg_visibility: Restrict access to more relation types

Temporary relations of other sessions have their own local pages.
Temporary and unlogged relations have no storage during recovery.
pg_visibility did not check for either cases, leading to inconsistent
results or confusing error messages, like some "ERROR: could not open
file".

This commit adds checks for both cases, so as a clean errors are
returned instead of the previous mix of incorrect results or errors,
depending on the function called and the relation whose information is
requested.

Author: Jim Jones <jim(dot)jones(at)uni-muenster(dot)de>
Reported-by: Zsolt Parragi <zsolt(dot)parragi(at)percona(dot)com>
Reviewed-by: Kirill Reshke <reshkekirill(at)gmail(dot)com>
Reviewed-by: Michael Paquier <michael(at)paquier(dot)xyz>
Reviewed-by: Surya Poondla <suryapoondla4(at)gmail(dot)com>
Discussion: https://postgr.es/m/82ba0876-6127-4770-b900-aa1bd52abfed@uni-muenster.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/1ed083f90d29871b21d5b3d2351accf4a0d9ca81

Modified Files
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contrib/pg_visibility/pg_visibility.c | 31 +++++++++++++++++++++----------
1 file changed, 21 insertions(+), 10 deletions(-)