Add Support for ScoreV2 in Standard Difficulty Calculations

[Finadoggie]

This does not affect ranked play whatsoever. However, if sorting leaderboards by pp is implemented, this will affect local leaderboards with imported sv2 scores. Also (probably) impacts any community-made tournament pp calculators.

tl;dr this change doesn't have much reach but the performance impact is one if statement so I see no reason not to have it

[Finadoggie]

meant to target pp-dev, not master

[mcendu]

Stable ScoreV2 scores probably shouldn't carry the Classic mod on import, since ScoreV2 is pretty close to Lazer's scoring and behavior.

[BunnyTub]

The Classic mod should still be carried in my opinion, as slider head accuracy and slider functionality differ. ScoreV2 on stable attempts to scale all hit object scoring values to a hard limit of 1 million at 1.00 Score Multiplier (excluding bonus spinner values in osu!, dendens in osu!taiko, and collected bananas in osu!catch). Taken that part from the wiki. It means that while the scoring methods are similar, they aren't the same, even with the score cap, if that makes sense.