Add a toggle to the GUI for the 'use_http3_upstreams' setting

### Prerequisites

- [X] I have checked the [Wiki](https://github.com/AdguardTeam/AdGuardHome/wiki) and [Discussions](https://github.com/AdguardTeam/AdGuardHome/discussions) and found no answer

- [X] I have searched other issues and found no duplicates

- [X] I want to request a feature or enhancement and not ask a question

### The problem

It would be nice if there was a GUI toggle to enable/disable the 'use_http3_upstreams' setting in the Upstream DNS servers settings area. This is more user friendly than having to change the setting in the yaml settings file.

### Proposed solution

Add a GUI toggle switch below 'Fastest IP address' (or where ever you think it would work best) to enable or disable the 'use_http3_upstreams' setting.

Something like the following;

`Use HTTP/3 upstreams: Upgrade encrypted DNS-over-HTTPS connections to HTTP/3 when available.`

### Alternatives considered and additional information

_No response_