Change maxed main stat toggle to dropdown

[Sethyboy0]

Description

• Changed "maxed main stat" toggle on the optimizer to a dropdown that allows you to pick what level the relics are upscaled to. The current values are 3/6/9/12/15 with a default value of 12. Anything below 9 isn't very useful but it doesn't cost anything to add.
• Added some typing stuff to get TS to stop bitching at me. I can remove it from the PR if you don't want it.
• Moved some relic calculation code to a utils file to share it between this dropdown's effects and the relic page.

The reasoning behind this is to help newer players like myself, my wife, and my friend who are just hitting TL 65 and are starting to seriously push the endgame modes. Relic exp costs scale exponentially while the gains are mostly linear and for the price of a +15 relic you can have 2 +12s or 4 +9s. This dropdown lets us help determine which relics are worth using our resources on, especially as we deal with relics we know will later get replaced because of limited substat choices.

https://honkai-star-rail.fandom.com/wiki/Relic/EXP

Pic:

Optimizing my acheron with +15 selected (matches with master):

Now with +12 selected:

I also updated the help text, though there's probably a better way to word things:

Maybe calling it "Relic upscale level" and changing the bottom settings to say "minimum" would be better?

Checklist

• [ ] I have added commit messages that are descriptive and meaningful.
• • I'll update the commits later if/when we actually want to merge it.
• [x] I have tested the changes locally.
• [x] I have reviewed the code changes.