Multiball_locks balls_to_replace is not dynamically configurable

[jimhenshaw]

I recently ran into a situation where I wanted to add a ball to a multiball lock without automatically replacing the ball. It's not dynamically configurable though. The config value could be turned into a template to allow this functionality.

config_spec.yaml:1039 multiball_locks::balls_to_replace

balls_to_replace: single|int|-1

change to

balls_to_replace: single|template|-1

This would require updating multiball_lock.py _lock_ball function use of balls_to_replace, which is the only use of balls to replace.

 # schedule eject of new balls for all physically locked balls
        if self.config['balls_to_replace'] == -1 or new_locked_balls <= self.config['balls_to_replace']:
            self.info_log("%s locked balls and %s to replace, requesting %s new balls",
                          new_locked_balls, self.config['balls_to_replace'], balls_to_lock_physically)
            self._request_new_balls(balls_to_lock_physically)
        else:
            self.info_log("%s locked balls exceeds %s to replace, not requesting any balls",
                          new_locked_balls, self.config['balls_to_replace'])

update to replace self.config['balls_to_replace'] with self.config['balls_to_replace'].evaluate([])

reference template implementation: https://github.com/missionpinball/mpf/pull/1901/files