added DNS Seeder in Marmara codebase

[rumeysayilmaz]

created A-records for seeds.marmara.io and added DNS Seeder in Marmara codebase as described in here

built from this branch on Ubuntu 20.04 machine:

Upon starting marmarad:

2024-10-09 12:14:06 dnsseed thread start
2024-10-09 12:14:06 Loading addresses from DNS seeds (could take a while)
2024-10-09 12:14:06 net thread start
2024-10-09 12:14:06 opencon thread start
2024-10-09 12:14:06 addcon thread start
2024-10-09 12:14:06 msghand thread start
2024-10-09 12:14:06 init message: Done loading
2024-10-09 12:14:06 marmara: MARMARA_POS_IMPROVEMENTS_HEIGHT=110777
2024-10-09 12:14:06 marmara: no '-pubkey' set, use -pubkey for mining
2024-10-09 12:14:12 3 addresses found from DNS seeds
2024-10-09 12:14:12 dnsseed thread exit