Add Validator MetaData

BlockScout provides metadata on Validators of POA Core and POA Sokol chains.

Click to view validator info, icon only appears for validators.

Validator details

This information is sourced through the Validators Contract and the Validator Metadata Contract. These contracts are defined through environment variables located here:

https://github.com/poanetwork/blockscout/blob/12aa15671142af00b35ff05aeac107c2c686c4c8/apps/explorer/config/config.exs#L33-L41

Content moved from https://forum.poa.network/t/how-to-add-validators-metadata-to-blockscout/1949