Improve iOS first run / empty view

[cjdowner]

Currently when you launch Balance on iOS for the first time / when you remove all your accounts, you get this screen. It's good how there's a placeholder and it's not totally blank - but perhaps this can be improved.

The Mac has a really nice Accounts view, so perhaps the two can be merged...

Dirtiest of hacks. Christian can make it 1000* nicer

There would be a general UX benefit here, and that means you can tap directly into adding the account setting, instead of a view where you have to select your account from a list.

I'm sure this is already in progress, but filing to make it actionable

[einsteinx2]

@christianbaroni interested in your take on this. For now we'll keep this postponed as it matches the macOS app and we have too much other work to do.