Allow per-column foreign data wrapper options.

doc/src/sgml/catalogs.sgml

doc/src/sgml/information_schema.sgml

doc/src/sgml/ref/alter_foreign_table.sgml

doc/src/sgml/ref/create_foreign_table.sgml

doc/src/sgml/ref/psql-ref.sgml

src/backend/access/common/tupdesc.c

src/backend/catalog/genbki.pl

src/backend/catalog/heap.c

src/backend/catalog/information_schema.sql

src/backend/commands/tablecmds.c

src/backend/nodes/copyfuncs.c

src/backend/nodes/outfuncs.c

src/backend/parser/gram.y

src/backend/parser/parse_utilcmd.c

src/bin/pg_dump/pg_dump.c

src/bin/pg_dump/pg_dump.h

src/bin/psql/describe.c

src/include/catalog/catversion.h

src/include/catalog/pg_attribute.h

src/include/catalog/pg_class.h