[Cosmos DB] Rename ConnectionStringSetting and collection

[ealsur]

Other extensions are using the name Connection for attribute mapping that works for connection strings (example https://github.com/Azure/azure-sdk-for-net/blob/main/sdk/eventhub/Microsoft.Azure.WebJobs.Extensions.EventHubs/src/EventHubAttribute.cs#L33) but would also work for AAD information.

Since we are already on a breaking change train (moving to V3 SDK), might as well rename it to be consistent (anyway, using ConnectionStringSetting would not sound great for AAD).

As part of the naming alignment, V3 SDK documentation talks about Containers, not Collections anymore, so the property names like CollectionName are renamed to ContainerName.

[fabiocav]

@ealsur looks good. As long as this is going in a new major version.

Thanks for sending refactoring work like this as a standalone PR!