feature request: provide --restore-target-wal to pg_rewind (from PG13)

Hello,

Use case: From Postgres 13 when pg_rewind don't succeed on resynchronizing former primary, just because some WALS are missing, it is now possible to tell pg_rewind to look for them in WAL archives with option --restore-target-wal

pg_auto_failover under the hood uses pg_rewind to synchronize former primary with current one.
When pg_rewind fails it triggers a full backup of current primary (through pg_basebackup )

This requires handle of restore_command in pg_autofailover (new parameter) , not only when resyncing former primary but also when building new replicas.
And, probably, add a new parameter to turn replication slots optionnals (because you mostly don't need it when using log fishing replication e.g. using restore_command).

Today modern storage solutions Azure blob, S3 like formats, provide a remote storage for the backup repository (all without ssh), this is why restore_command parameter has turn a new life.

It is not that easy, but if we can avoid a full backup (particularly through pg_basebackup) it's worth it, particularly on very large databases.
Nowadays, most advanced automatic failover tools handle this use case.

Thank you
Tiago ANASTACIO