add built in challenge for crypto names

[estebanabaroa]

there should be a built in challenge for validating crypto names, for example if someone has a .eth, you give him 1 free reply per hour, 1 free post per day and 0 free votes per hour (giving free votes would be easy to game I think).

I guess it would work like this

const cryptoNameAuthorAddressChallegeSubplebbit = {
  title: 'crypto name author address challenge subplebbit',
  settings: {
    challenges: [
      {
        name: 'crypto-name-author-address',
        options: {
          tlds: ['eth', 'sol'],
        },
     ]
  }
}

TODO: figure out how to add rate limit and fallback challenge