Added tests related to operation feedback agent capabilities.
Added tests related to operation feedback agent capabilities.

These tests verify that master and agent behavior is correct
during a downgrade of an agent to one which does not have the
AGENT_OPERATION_FEEDBACK capability, and when a new agent's
capabilities are altered such that it no longer has the
RESOURCE_PROVIDER capability set.

Review: https://reviews.apache.org/r/69964/

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