Add Arenas to custom lobbies

@BigMacAttack8u
The only changes it SHOULD endure are the new weapons and legends.
Alter didn't exist.
I don't think Catalyst existed.
Vantage existed in the last couple months so she should be implemented into it.

I don't think the Nemesis was in there. Akimbos definitely weren't. Nor was Gun Shield or the reverse stability hipfire of all LMGs.
And the shotgun alterations affecting mastiff and peacekeeper.

Such updates need a minor conversion to the system of arenas. Costs and whatnot. Rating. Levelling.

I'm pretty sure all weapons were in the shop. Am I mistaken since it's been so long? Were there some missing that existed in royale at the time?

Oh, I'm forgetting the charge rifle alteration, or reversion from my view because that's how it worked in Titanfall 2, the current version, whereas previous had me questioning its purpose. I can definitely make 10 times more damage with current than previous. One solid hit rather than tap and can't hit em again.

@Zulkiers I’m not saying added weapons and legends, i’m saying i don’t want the core gameplay of arenas to be changed. Balancing and the introduction of the new weapons and legends are good changes. i Just really don’t want them to change the round system the buy system, or the fact that an ash variant is the announcer / game controller. I just want arenas back in the same way it was gameplay / experience wise (minus the cheaters ofc).