Support managed identity login

**Describe the bug**
This is more of a feature request than a bug.

It's not possible to use Azure's managed identity feature for login (MSI). I noticed that the library used for authentication, `@azure/ms-rest-nodeauth` actually supports MSI login, but this lib does not make use of it. I tried to modify the source of ng-deploy-azure to call that functionality, but because the dependency uses a very old version of ms-rest-nodeauth, it tries to authenticate to MSI an approach that is now deprecated (uses localhost instead of IMDS -- https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/howto-migrate-vm-extension).

**To Reproduce**
Steps to reproduce the behavior:
1. Turn on Managed Identity for a VM
2. There is no way to tell ng-deploy-azure to use the now-logged-in MSI.

**Expected behavior**
1. Turn on Managed Identity for a VM
2. Have a way to tell ng-deploiy-azure to use MSI credentials (should work even if env var CI=1 is set)
3. Deployment command should use the MSI identity to access storage and deploy

**Screenshots**
If applicable, add screenshots to help explain your problem.

**Desktop (please complete the following information):**
N/A

**Smartphone (please complete the following information):**
N/A

**Additional context**
I was mainly looking for this feature because we want to use this package in our CI, but we don't want hardcoded user/passwords (i.e. service principal client ID and secret) written into our code or configs. An alternative would be to use an SP that is backed by a certificate in Azure Keystore but you don't support that either.