pgsql: Add String object access hooks

Add String object access hooks

This caters for cases where the access is to an object identified by
name rather than Oid.

The first user of these is the GUC access controls

Joshua Brindle and Mark Dilger

Discussion: https://postgr.es/m/47F87A0E-C0E5-43A6-89F6-D403F2B45175@enterprisedb.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d11e84ea466b4e3855d7bd5142fb68f51c273567

Modified Files
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src/backend/catalog/objectaccess.c | 140 +++++++++++++++++++++++++++++++++++--
src/backend/utils/misc/guc.c       |  17 +++++
src/include/catalog/objectaccess.h |  70 ++++++++++++++++++-
src/include/nodes/parsenodes.h     |   4 +-
src/include/utils/acl.h            |   4 +-
5 files changed, 226 insertions(+), 9 deletions(-)