ECH (Encrypted Client Hello) support for DNS-over-HTTPS

### Issue Details

Hello,

please add support of ECH (Encrypted Client Hello) support for DNS-over-HTTPS.

Thank you.
Best regards

### Proposed solution

I'm not talking about records like HTTPS - it is already supported, I know. I'm talking about encrypting the transmission of servername to the DoH host itself😊Possible related to https://github.com/AdguardTeam/AdGuardDNS/issues/918

### Alternative solution

_No response_