Add startup screen as FreeRDP loads

In some cases there is a slight delay before FreeRDP initiates and displays the connection. This can cause a user to "restart" an application again, or 're-double-click" a file again. To overcome this, build in a system that shows a loading mechanism prior to the actual FreeRDP display appearing.

This will become more pertinent as the ability to pause a VM when not in use is added.