Add DNSCrypt support to personal AdGuard DNS

### Issue Details

We currently only support DoH / DoT / DoQ there. It would be logical to add DNSCrypt support as well.

### Proposed solution

In order to make "personal" part work we can use "Provider Name" field to recognize the user that makes a query. This "provider name" will be sent to AdGuard DNS server when fetching the certificate. Once we receive such a query, we can return a personal certificate of that user and then use the "Client Magic" value of that cert to recognize user's encrypted queries.

### Alternative solution

_No response_