Also disable Attach button for kernel.
Add UI window for starting a new team.
Wire up Start new team button.
Add message for starting a new team. Implements #9682.

- The Debugger app now accepts a message asking it to start a new team.
  It attempts to do so given the path and arguments, and passes the
  result back to the sender if desired.
Minor tweak to allow window to be resizable.
Cleanups.