Support --init-replication-factor flag

--init-replication-factor is a command-line argument of every instance.

replication_factor is a property of the whole cluster

1. Parse command line arguments.
2. Persist it in the clusterwide config.

Pass the parameter to https://git.picodata.io/picodata/picodata/picodata/-/blob/929cead1235ad58e428c303f405af4e081baf0d7/src/traft/node.rs#L585