Add Cosmos DB integration tests using an emulator

**Is your feature request related to a problem? Please describe.**
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**Describe the solution you'd like**
Add integration tests similar to SQL Server and SQLite for our Cosmos DB metadata store: https://docs.microsoft.com/en-us/azure/cosmos-db/local-emulator#running-on-docker

Locate the existing SQL Server and SQLite integration tests and the Cosmos DB metadata store. Read how those test suites configure their databases, then consult the linked Azure Cosmos DB emulator documentation for Docker setup. Done means equivalent Cosmos DB integration tests run successfully against the emulator.

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