Fix resource deletions not propagating through service instances

[joelhulen]

Fix resource deletions not propagating through service instances

The issue or feature being addressed

Other instances were not picking up the change when deleting a resource, such as an Agent. For example, the Agent would still appear in the User Portal after deleting it in the Management Portal, or it would reappear in the Management Portal when hitting a different instance of the Management API.

Details on the issue fix or feature implementation

Adds custom equality operators to the ResourceReference class and evaluates in-memory resource references against the list of persisted references, updating the in-memory reference if it is different.

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• I have included unit tests for the issue/feature
• I have included inline docs for my changes, where applicable
• I have successfully run a local build
• I have provided the required update scripts, where applicable
• I have updated relevant docs, where applicable

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