[Feature Request] iOS: Make DNS provider list on par with dashboard generated config

[ink-splatters]

Hi,

Thanks for a great app!

My request is about DNS provider list in latest iOS app: it seems to lack several providers, in particular, Quad 9 which I'm interested in.

Is there a reason for it? Otherwise, can you please add it?

One more thing: it would be nice (in either app) to choose DNS Provider along with corresponding protocol, e.g., two radios which filter the list:

DNS

🔘 DoH
🔘 DoT

<Providers List>

```

[maxaldenm]

I have the same concerns and want to see Quad9 implemented too.