[debug] Disable the debug toolbar item, when the selected board is not attached

[kittaakos]

Describe the bug
When I select a not connected board (port is not set), I can start the debugging as the debug toolbar is active, but without an attached board and the port, and it won't work. Shall we disable the debug toolbar, @ubidefeo?

screencast.2021-04-08.09-13-02.mp4

[ubidefeo]

Leaving this tab available, allows advanced users to manually define a debug launch configuration.
I think it should stay there