[Suggestion] Crossplay enablement

[patrickfey]

I found e.g. on Nitrado ACC PS5 Servers that there is a options in the settings.json for "isCrossplayServer". Please have that one introduced on accweb aswell. Values can be 0 (no) and 1(yes). It's for whatever reason nowhere documented

[patrickfey]

#283

• Please review and perhaps someone can test it, since I didn't know how to run it properly locally