Devide DTCLProxy into DTCLSingleShardProxy, DTCLMultiShardProxy and
DTCLPrefixShardProxy to address the different registration mechanisms
used in all three cases.
JIRA: CONTROLLER-1932
Change-Id: I48732577f26fa5844b69a2feaddb02fe53909da7 Signed-off-by: Tibor Král <tibor.kral@pantheon.tech> Signed-off-by: Robert Varga <robert.varga@pantheon.tech>