Using my own CA with Adguard

I see that AdguardCli uses a self-signed CA for https filtering, but I would like to use my very own CA for this which has deployed to all my devices at system level. The idea is to let AdguardCLI use a intermediate CA signed by my root CA, but ./SSL/cert.db doesn't look like readable by certutil, or in other well-known comprehended format.

```
-> % ls
'AdGuard CLI CA.cer' cert.db
-> % certutil -L -d .
certutil: function failed: SEC_ERROR_BAD_DATABASE: security library: bad database.
-> % hexdump cert.db -n 8
0000000 93be 4bb6 7821 962b
0000008
```