This commit removes ISkinnableSwell for taiko swell animations. In place
of it, an event named UpdateHitProgress is added to DrawableSwell, and
the skin swells are converted to listen to said event and
ApplyCustomUpdateState, like how spinner skinning is implemented for
std.
Also removes a weird sizing application that seems to have no effect
(introduced in 27e63eb; compare removals for other taiko DHO types in
9d00e5b and 58bf288).