Restart Connector upgrades

When a new version of the connector software is released, each connector makes 5 attempts to upgrade. If the upgrade fails to install and the connector fails to verify it's healthy after 5 attempts, the connector enters the "failed" state. The connector also blocks all other connectors in the tenant from upgrading until Citrix intervenes to restart the upgrade. In some cases, the cause of the failures is only intermittent or can be resolved by the customer. However, there has been no way for the customer to restart the upgrade once the issue is resolved. This feature introduces a mechanism for customers to retry upgrades on connectors in the "failed" state without Citrix intervention.