[WIP] Add support for ecql DOES-NOT-EXISTS to persistent store

[glenhein]

What does this PR do?

Add support for ecql DOES-NOT-EXISTS to persistent store. Includes a new unit test.

[Note] This PR is so the team can review the approach. The code needs to be cleaned up before it can be committed.

Who is reviewing it?

Select relevant component teams:

Ask 2 committers to review/merge the PR and tag them here.

How should this be tested?

Any background context you want to provide?

What are the relevant tickets?

Fixes: #____

Screenshots

Checklist:

• [ ] Documentation Updated
• [ ] Update / Add Threat Dragon models
• [ ] Update / Add Unit Tests
• [ ] Update / Add Integration Tests

Notes on Review Process

Please see Notes on Review Process for further guidance on requirements for merging and abbreviated reviews.

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