Make serial replication as a option for a peer instead of a table

Discussed with zghaobac and openinx offline, HBASE-20147 can only be solved by adding new stages when creating a new replication peer. It will also effect he processing even if you do not have any table with serial replication. And also, the new logic introduced in ReplicationSource related classes will also be executed even if you do not have serial replication tables.

So, we think that it maybe a better choice to move the option to ReplicationPeerConfig. Since if there is one table in the peer requires serial replication, then all the tables in this peer will be automatically 'serial' since the wal for these tables are mixed with the one which requires serial replication.