Add Hagezi's Social Networks DNS Blocklist

### Prerequisites

- [x] The blocklist is created specifically for DNS-level blockers;
- [x] The blocklist is regularly updated (at least 10 updates per month);
- [x] The blocklist is known and popular;
- [x] The blocklist satisfies [the repo requirements](https://github.com/AdguardTeam/HostlistsRegistry#-what-blocklists-can-be-added-here);

### Blocklist name

HaGeZi's Social Networks DNS Blocklist

### Blocklist category

Other

### Homepage

https://github.com/hagezi/dns-blocklists

### Explanation

I would request that Hagezi's Social Networks DNS Blocklist (https://raw.githubusercontent.com/hagezi/dns-blocklists/refs/heads/main/adblock/social.txt) be added as a built-in filter option to AdGuard Private DNS that users can choose to enable. Hagezi's DNS blocklists are very well maintained and supported. Hagezi's Gambling and Piracy blocklists are already offered as built-in lists and I believe his other lists should also be offered as a built-in option for users to enable if they choose to.