Implement relax mod for taiko

[bdach]

RFC. Closes #7914.

The lack of this in lazer has been bugging me for a while.

This is a second try at implementing this. In the first one I tried to follow this idea of mixing input blockage and re-propagation of inputs to avoid changing hitobject classes. However, it didn't work because #3493 and #25010 will not allow it to work due to the "has input been handled this frame already" checks. Therefore if I was going to have to modify DHOs anyway to bypass that check then I beelined for the simplest possible / most obvious implementation instead. And yes it's slightly different than stable in behaviour because it doesn't "correct" user inputs like stable but /shrug at this point.

Also stable relax does the following things:

• turns off a drum roll anti-mashing provision that doesn't even exist in lazer anymore
• prevents failure - but other relax mod implementations in lazer don't do this, so neither does this

[Ratchet0203]

Probably out of scope for this PR, but I suggest removing color SR in taiko diffcalc for this mod since you can ignore colors.

[bdach]

200% out of scope, mod is unranked by default anyway. Something for @ppy/taiko-pp-commitee to worry about if this survives review.

[smoogipoo]

lgtm