To specify upstream DNS servers for a file containing a set of domain

### 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

Make it more flexible to specify the configuration of upstream DNS servers from files

### Proposed solution

I know that there is already a feature "Loading upstreams from file", but I want to use it more conveniently, rather than configuring upstream DNS servers from a single file through a configuration file. Suppose I have two files, microsoft and sony, which contain the domain sets of Microsoft and Sony.
I hope that the configuration of upstream DNS servers on the web page can be set like this
[file:microsoft]1.1.1.1
[file:sony]8.8.8.8

Of course, if you can support the domain set of the project https://github.com/v2fly/domain-list-community, that would be great. It is implemented by using the dlc.dat file
[file:dlc.dat:filename]upstream
For example
[file:dlc.dat:microsoft]1.1.1.1
[file:dlc.dat:sony]8.8.8.8

### Alternatives considered and additional information

_No response_