Allow pg_upgrade to copy segments of the same relfilenode in parallel

When Who What
2022-08-02 18:58:04 Jacob Champion (jchampion) Closed in commitfest 2022-07 with status: Returned with feedback
2022-03-28 14:24:33 Justin Pryzby (justinpryzby) Closed in commitfest 2022-03 with status: Moved to next CF
2022-03-22 00:34:28 Andres Freund (andresfreund) New status: Waiting on Author
2022-02-02 03:07:38 Jaime Casanova (jcasanov) Changed authors to Jaime Casanova (jcasanov)
2022-02-02 03:07:06 Jaime Casanova (jcasanov) Attached mail thread Yfny/GbI7no+hdTs@ahch-to
2022-02-02 03:07:06 Jaime Casanova (jcasanov) Created patch record