Allow overriding DDR response

[yegle]

Prerequisites

• I have checked the Wiki and Discussions and found no answer

• I have searched other issues and found no duplicates

• I want to request a feature or enhancement and not ask a question

The problem

I'm using Caddy reverse proxy in front of AdGuard Home so that I can restrict the access to the admin console while providing a public-accessible DNS-over-HTTPS service. Caddy also handles HTTP3/Quic on UDP port 443 which I thought is great.

But then I realized:

1. If I set DoQ port to 443 in the settings, AdGuard will fail to start.
2. If I do not set DoQ port to 443, then the DDR response will include a port that I do not open on my firewall:

$ kdig +short @MY-HOST +https _dns.resolver.arpa type64
1 MY-HOST. alpn=h2 port=443 key7="/dns-query{?dns}"
1 MY-HOST. alpn=doq port=784

3. If I set DoQ port to empty string, the DDR response will omit the DoQ information:

$ kdig +short @MY-HOST +https _dns.resolver.arpa type64
1 MY-HOST. alpn=h2 port=443 key7="/dns-query{?dns}"

Proposed solution

It looks like the easiest way is to allow us to customize the DDR response, so that I can set DoQ port in the DDR response to 443.

Alternatives considered and additional information

No response