UI for configuring upstreams per domain

### Suggestion

Add function that specify upstreams for domains List , just like the other lists.
(AGH can [specify upstreams for domains](https://github.com/AdguardTeam/AdGuardHome/wiki/Configuration#upstreams-for-domains) manually for now)

### Sence

AGH can specify upstreams for domains, but it's hard to input if I want set upstream for amount of domians. I've got a list of domains which are polluted by ISP, but access the safe DNS server in CN means high latency and unstable. I think it will improve the performance of AGH if it can set upstream for selected list.