Remove Routed RPC concept and implementation

Routed RPCs are OpenDaylight-specific extension to YANG 1.0 RPCs, which are effectively achieving the same functionality as YANG 1.1 actions.

Using them in modeling as well as in code is a bit arcane as users need to understand what yang-ext:context-reference and yang-ext:context-instance do on the semantic level to make the connection that they are all about meeting on an instance-identifier.

Since we have YANG 1.1 actions available, we should migrate to use them. This implies they are only available through RFC8040 RESTCONF – which needs to be release noted for each component completing the migration.

Once we have migrated all our users, we should remove all the complexity and duality associated with supporting both normal and routed RPCs.