Add support for user-assigned managed identity connections

[ryan-adler]

Is there an existing issue for this?

• I have searched the existing open and closed issues

Description

While there seems to be support for System-Assigned MSI connection strings, when trying to use a user-assigned identity (ie. add "User Id=xxxxxxx-xxxx-xxx-xxxx" to the connection string), the deployment fails with the message:
Cannot set the AccessToken property if 'UserID', 'UID', 'Password', or 'PWD' has been specified in connection string.

What is the impact?

Only system-assigned MSI can be used in the SQL connection