Add platform movement indicators#906

For all the work that Rivals 2 puts into QoL and communicating information to players, the lack of visual stage elements that indicate when platforms are about to move/spawn comes across as an odd omission, especially considering older games like P+ and the original Rivals of Aether have them. This feature would be very helpful on stages like Julesvale and Air Armada to help players not get caught off-guard by sudden platform movements, without having to resort to memorizing movement timers and looking at the timer mid-match.