Private VNET address should be selectable

**Describe the bug**
When running Batch Explorer on a locked down private VNET, the connection dialogue defaults to a public load balancer address which is not reachable from the private VNET, rendering this convenience feature inert.

**To Reproduce**
Create a private VNET, standup Batch explorer on a node in that network, deploy a batch pool into it and attempt to connect directly to pool nodes.

**Expected behavior**
Expected Batch Explorer to default to the private VNET associated with the batch pool, or perhaps offer it as an option / make it switchable between the networks.