Debugger: Fix incorrect behavior when asking to activat.

GraphicalUserInterface:
- The Show() method now checks if the team window is already visible. If
  it is, we instead call Activate() to focus it. Fixes the problem that
  attempting to attach to a team which we already had a running team
  debugger for would appear to do nothing, rather than focusing that window.

src/apps/debugger/user_interface/gui/GraphicalUserInterface.cpp

@@ -178,7 +178,10 @@ GraphicalUserInterface::Init(Team* team, UserInterfaceListener* listener)
 void
 GraphicalUserInterface::Show()
 {
-	fTeamWindow->Show();
+	if (fTeamWindow->IsHidden())
+		fTeamWindow->Show();
+	else
+		fTeamWindow->Activate();
 }