Updated master operation handling to account for new agent capability.
Updated master operation handling to account for new agent capability.

Since the new AGENT_OPERATION_FEEDBACK capability has been
made required for agent startup, we need to update the way
the master handles validation of incoming operations and
acknowledgement calls to account for cases where each of
the AGENT_OPERATION_FEEDBACK and RESOURCE_PROVIDER
capabilities are enabled/disabled.

Review: https://reviews.apache.org/r/69957/

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