Authorize Services w/ Managed Identity

[pmcvtm]

Replace regular 'ol authorization schemes (keys, service principals, passwords) for Azure Clients with Managed Identity

• use token + storage URI for blobs
  • replacing connection string + container name
• add token to EF connection at Context build-time
  • replacing username + password in connection string
• use Default token for KeyVault
  • replace explicit token that used AD App + client secret

At its current state, the app won't run locally; it's just for in-Azure