Currently our subdomain app URLs are:

• <port>--<agent>--<workspace>--<username>
• <app>--<agent>--<workspace>--<username>

App names are already unique per template, enforced at the provisioner level. The second format can most likely be changed to allow for <app>--<workspace>--<username> to save URL space.

Relates to #15178, as it'll help make URLs smaller