pgsql: Fix loose ends for SQL ACCESS METHOD objects

Fix loose ends for SQL ACCESS METHOD objects

COMMENT ON ACCESS METHOD was missing; add it, along psql tab-completion
support for it.

psql was also missing a way to list existing access methods; the new \dA
command does that.

Also add tab-completion support for DROP ACCESS METHOD.

Author: Michael Paquier
Discussion: https://www.postgresql.org/message-id/CAB7nPqTzdZdu8J7EF8SXr_R2U5bSUUYNOT3oAWBZdEoggnwhGA@mail.gmail.com

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/4f04b66f97f0e0265489f0fe0373ea44c9ad11bf

Modified Files
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contrib/bloom/bloom--1.0.sql | 1 +
doc/src/sgml/ref/comment.sgml | 4 +++
doc/src/sgml/ref/psql-ref.sgml | 13 +++++++++
src/backend/parser/gram.y | 8 ++++--
src/bin/psql/command.c | 3 ++
src/bin/psql/describe.c | 64 ++++++++++++++++++++++++++++++++++++++++++
src/bin/psql/describe.h | 3 ++
src/bin/psql/help.c | 1 +
src/bin/psql/tab-complete.c | 15 ++++++++--
9 files changed, 107 insertions(+), 5 deletions(-)