Microsoft has updated the golang Azure SDK significantly. Update the
azure storage driver to use the new SDK. Add support for client
secret and MSI authentication schemes in addition to shared key
authentication.
Implement rootDirectory support for the azure storage driver to mirror
the S3 driver.
Signed-off-by: Kirat Singh <kirat.singh@beacon.io>
Co-authored-by: Cory Snider <corhere@gmail.com>
