ipfs network support

[cortze]

This PR summarized the changes needed to update Armiarma Crawler to perform in multi libp2p-based networks.

This specific PR focuses on the IPFS network and related projects, such as Filecoin.

The proposed changes increase the modularity of the tool adding:

• github.com/urfave/cli/v2 for multi-command support
• new discovery interface to plug any new discovery module