pgsql: Move common pg_dump code related to connections to a new file

Move common pg_dump code related to connections to a new file

ConnectDatabase is used by pg_dumpall, pg_restore and pg_dump so move
common code to new file.

new file name: connectdb.c

Author:    Mahendra Singh Thalor <mahi6run@gmail.com>

Branch
------
master

Details
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https://git.postgresql.org/pg/commitdiff/c1da7281060d646f863e920a1aac3b9dbc997672

Modified Files
--------------
src/bin/pg_dump/Makefile             |   5 +-
src/bin/pg_dump/connectdb.c          | 294 +++++++++++++++++++++++++++++++++++
src/bin/pg_dump/connectdb.h          |  26 ++++
src/bin/pg_dump/meson.build          |   1 +
src/bin/pg_dump/pg_backup.h          |   6 +-
src/bin/pg_dump/pg_backup_archiver.c |   6 +-
src/bin/pg_dump/pg_backup_db.c       |  79 ++--------
src/bin/pg_dump/pg_dump.c            |   2 +-
src/bin/pg_dump/pg_dumpall.c         | 278 ++-------------------------------
9 files changed, 352 insertions(+), 345 deletions(-)