Add criptolayer.net DNS seeders

Summary: Add mainnet and testnet3 DNS seeders from criptolayer.net

Test Plan:
Verify service, e.g.
$ dig seeder.criptolayer.net
$ dig testnet-seeder.criptolayer.net

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Differential Revision: https://reviews.bitcoinabc.org/D390