feat: prep some stuff for lighthouse forms multiselect

[hjpalpha]

Summary

currently forms pass a csv value when using input type=checkboxes
with the new lighthouse forms that option will be converted to multiselect
multiselect will pass json instead of csv to the modules
hence add a functio for parsing both and adjust a few modules that are used by forms on sc2 with input type=checkboxes so that they do not break with LH conversion

After merge

• Adjust the following non git modules on sc2 too:
  • Module:PlayerStatistics
  • Module:HeadToHead
• check open PRs for needed adjusts

How did you test this change?

dev

[ElectricalBoy]

maybe put Array.parseMultiSelect under Module:Forms/Util or something where we could potentially add form-related helper functions? I'm just thinking out loud

[hjpalpha]

maybe put Array.parseMultiSelect under Module:Forms/Util or something where we could potentially add form-related helper functions? I'm just thinking out loud

fwiw not sure on the name and also not sure on putting it into array
was just the first thing that came to mind

regarding Module:Forms/Util
i thought about something like that, but discarded it because its usage is not really related to forms
like the modules the forms use aren't only used in those forms but also in other places
so to me it feels wrong to use formUtils in modules that are primarily not used in forms