pgsql: pg_dump: Allow dumping data of specific foreign servers

pg_dump: Allow dumping data of specific foreign servers

The new command-line switch --include-foreign-data=PATTERN lets the user
specify foreign servers from which to dump foreign table data. This can
be refined by further inclusion/exclusion switches, so that the user has
full control over which tables to dump.

A limitation is that this doesn't work in combination with parallel
dumps, for implementation reasons. This might be lifted in the future,
but requires shuffling some code around.

Author: Luis Carril <luis(dot)carril(at)swarm64(dot)com>
Reviewed-by: Daniel Gustafsson <daniel(at)yesql(dot)se>
Reviewed-by: Surafel Temesgen <surafel3000(at)gmail(dot)com>
Reviewed-by: vignesh C <vignesh21(at)gmail(dot)com>
Reviewed-by: Álvaro Herrera <alvherre(at)2ndQuadrant(dot)com>
Discussion: https://postgr.es/m/LEJPR01MB0185483C0079D2F651B16231E7FC0@LEJPR01MB0185.DEUPRD01.PROD.OUTLOOK.DE

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/2f9eb31320948b968e5f744b73032405e1f25225

Modified Files
--------------
doc/src/sgml/ref/pg_dump.sgml | 30 ++++++++
src/bin/pg_dump/pg_dump.c | 110 +++++++++++++++++++++++++--
src/bin/pg_dump/pg_dump.h | 1 +
src/bin/pg_dump/t/001_basic.pl | 14 +++-
src/bin/pg_dump/t/003_pg_dump_with_server.pl | 36 +++++++++
5 files changed, 185 insertions(+), 6 deletions(-)