Cloud Shell ManagedIdentitySource should throw if a user-assigned managed identity clientID or resourceID is supplied

[christothes]

If the Cloud Shell ManagedIdentitySource is detected via MSAL and a user-assigned managed identity clientID or resourceID is supplied, the ManagedIdentityCredential should throw.

The rationale for taking this minor breaking change is that CloudShell does not support specifying a clientID or ResourceID and the current behavior of silently falling back to attempting to use a system-assigned identity could be unexpected.