client_x509_auth for ODoH

[dhruvp141188]

When trying to connect to ODoH Servers, they are required to have client cert verification. And right now there is no way to specify that in toml file.

[jedisct1]

they are required

None of the relays (I guess you are referring to relays, not servers) require this as far as I know. That would be a little bit surprising.

Looking at the code, it seems like DoH queries and queries sent to ODoH relays use exactly the same code to connect, so credentials defined in the [doh_client_x509_auth] section should work for ODoH.