all: enhanced TLS certificate verification error messages

Added more descriptive error messages for TLS certificate verification
failures across DoH, DoT, DoQ, and DoH3 protocols. The error messages
now include:

- Certificate subject information
- Issuer organization details
- Common name of the certificate

This helps users and developers better understand certificate validation
failures by providing specific details about the untrusted certificate,
rather than just a generic "unknown authority" message.

Example error message change:
Before: "certificate signed by unknown authority"
After: "certificate signed by unknown authority: TestCA, TestOrg, TestIssuerOrg"

doq.go

@@ -43,7 +43,7 @@ func resolve(ctx context.Context, msg *dns.Msg, endpoint string, tlsConfig *tls.
 			continue
 		}
 		if err != nil {
-			return nil, err
+			return nil, wrapCertificateVerificationError(err)
 		}
 		return answer, nil
 	}