Debugger: Implement #9783.

TeamDebugger:
- When we're notified that the target team has called exec(), take all
  necessary steps to prepare. These include saving settings for the old
  team, clearing out breakpoints, resetting signal dispositions, and
  removing the old team's image list. Also set a flag indicating an exec
  is pending for later processing.
- On image load notification, if the pending flag is set, check if the
  new image is the app image, and if so update the team's name to
  the new image, load that respective team's settings, and set a
  temporary breakpoint in its main() so the user has a chance to
  perform any additional desired actions before starting execution
  in the new executable.

src/apps/debugger/controllers/TeamDebugger.h

@@ -184,6 +184,8 @@ private:
 			bool				_HandlePostSyscall(
 									PostSyscallEvent* event);
 
+			void				_PrepareForTeamExec(TeamExecEvent* event);
+
 			void				_HandleImageDebugInfoChanged(image_id imageID);
 			void				_HandleImageFileChanged(image_id imageID);
 
@@ -259,6 +261,7 @@ private:
 			TeamSettings		fTeamSettings;
 			int					fCommandLineArgc;
 			const char**		fCommandLineArgv;
+			bool				fExecPending;
 };