pgsql: Add pg_dump support for ALTER obj DEPENDS ON EXTENSION

Add pg_dump support for ALTER obj DEPENDS ON EXTENSION

pg_dump is oblivious to this kind of dependency, so they're lost on
dump/restores (and pg_upgrade). Have pg_dump emit ALTER lines so that
they're preserved. Add some pg_dump tests for the whole thing, also.

Reviewed-by: Tom Lane (offlist)
Reviewed-by: Ibrar Ahmed
Reviewed-by: Ahsan Hadi (who also reviewed commit 899a04f5ed61)
Discussion: https://postgr.es/m/[email protected]

Branch
------
REL9_6_STABLE

Details
-------
https://git.postgresql.org/pg/commitdiff/2b9d70159154a5ff6eb2d6f09db6f8da433328aa

Modified Files
--------------
src/bin/pg_dump/common.c | 1 +
src/bin/pg_dump/pg_dump.c | 104 ++++++++++++++++++++++++++--
src/bin/pg_dump/pg_dump.h | 1 +
src/test/modules/test_pg_dump/t/001_base.pl | 46 ++++++++++++
4 files changed, 146 insertions(+), 6 deletions(-)