VPP-1095 introduced a new API input queue and API handler table to be able to handle some messages as a client that already had handlers.

As the queues are not signaling the change of state they have to be checked periodically (if there are any new messages to be handled).

The state check for the new queue is done by a VPP process function in a loop which contains a suspend for small time. This greatly affects VPP performance.

To enhance performance we will replace binary API communication between CP and DP with direct communication using function calls and callbacks.