Have Metal Sonic use spinheight while dashing

Inspired by this GIF I saw in the Community Server a while back. Some Metal-exclusive paths already use this gating format, since he is the only character who can both roll and break spikes, but it makes sense to me that he should be able to plow straight through low gaps in his hunched over dash state. This removes the need to react to an upcoming gap with a roll, something I think makes pathing in this style awkward.

I've kept this feature exclusively for robots with DASH sprites to maintain as much compatibility with other addons as possible, though I'm not sure there are even other robots with dashmode who aren't hunched over. It would be nice to remove the sprite2 check if I can be sure the change doesn't create hitbox-to-sprite inconsistencies with any addon characters!

Since PlayerHeight hooks exist now, I've removed the sprite2 check. It now just affects all robots in dashmode and in dash state!