Option to make UI full width

### 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

Is there any way to make the overall UI full width? Currently the width is limited to 1200px but on wide screens this seems too compact and leaves a lot of empty space at the sides that would look better and be more usable if we had an option to switch to using full screen width available.

### Proposed solution

Maybe just a Fixed/Responsive checkbox would suit most use cases??

### Alternatives considered and additional information

_No response_