Split performance calculators

[stanriders]

This is a first step in making a proper lazer diff/pp calc. I'm not sure about the further direction I should take with the splitting yet, so I'm starting with just the safe refactor that doesn't require any infra-level changes

[peppy]

Blocking ahead of time pending discussion on a public forum at some later date.

[stanriders]

Blocking ahead of time pending discussion on a public forum at some later date.

I wanna clarify that this isn't something related to controversial things like rates and DA (at least with the current way diff/pp calc works). This is mostly just things that are a must for new score data
A hotfix pretty much, see this conversation

e: I've removed DA changes for now

[peppy]

It was brought up that this is a potential requirement for getting initial leaderboards online. @stanriders could you better describe what this is? Is the new class just a copy paste of the old one? Has it come from somewhere else?

Is there a reason we can't if certain parts of the main calculator rather than splitting into two? They should not differ that much. Maintaining two version is likely more complex than having one with pathing where required.

[stanriders]

It was decided that split won't be required any time soon so I'm closing this PR