Cosmos: Consider a Connection String value to disable SSL validation

[analogrelay]

One of the most common usages of Connection String auth is to connect to the Cosmos emulator (which doesn't support Entra ID, I believe). When doing this, it's useful for customers to be able to specify if SSL validation should be disabled in the connection string itself, since that allows the user to disable SSL validation only when running locally against the emulator, while preserving validation when running against a production endpoint. The .NET SDK supports this, so there's some prior art.

My main concern there is that we're also trying to move users off of connection strings in general, so I'm hesitant to add more functionality there unless we really need it. But we should discuss it.