Add append and remove peer table-cfs cmds for replication

HBASE-8751 introduces the tables/table-column families config for a replication peer. It's very flexible for practical replication in hbase clusters.

But it is easy to make mistakes during add or remove a table/table-column family for a existing peer, especially when the table-cfs is very long, for we need to copy the current table-cfs of the peer first, and then add or remove a table/table-column family to/from the table-cfs, at last set back the table-cfs using the cmd: set_peer_tableCFs.

So we implements two new cmds: append_peer_tableCFs and remove_peer_tableCFs to do the operation of adding and removing a table/table-column family. They are useful operation tools.