Limit simultaneously activated coins amount on iOS

[dth88]

#743 (comment)

I'm starting to get too many opened files on Xr in release mode with 9 coins already (around 210 from 250 descriptors used). So I think it might be worth to force users to not activate many coins for now for better and smoother user experience and disappointment avoiding :)

But if implement that we should carefully think about the case for users who'll update to this version and has more than 10 coins activated already (to prevent bricking/locking)

--reply:
12 sounds like a good number. Maybe we should make some users survey with questions how much coins do they use and how much have activated to ensure that limiation will not dissapoint em (#754).

Duplicated from private repo:
https://github.com/ca333/komodoDEX/issues/745