Add support for specifying connection string for Azure Uploader.

[Simrayz]

Is your feature request related to a problem? Please describe.
We are integrating livekit into our solution, and have been using Azurite for local testing. However, the azure adapter for the egress config does not support setting a connection string, and will always target https://%s.blob.core.windows.net/%s in uploader/azure.go.

Describe the solution you'd like
I would like to send a connection_string as a parameter to the upload config instead of both container_name and account_key when starting an egress service.