Add Libp2p config options to settings: TLS certificate for Secure Websockets

[mriise]

Summary

There should be some more config options for libp2p, mainly:

• bootstrap node addresses
• announce addresses
• path to TLS certificate for Secure Websockets

nice to haves:

• encrypt message content with shared key
• blacklisted peers
• explicit peers this is an optimization that we can skip for now

Problem

We don't have these options at the moment, having these are critical for a fully-fledged application running libp2p.

Solution

• Add options to the config file to change these settings.
• Dial bootstrapped addresses and add them to kademlia, via add_address (always).
• Keep track of a hashset/map (associated w/ the event_handler) of bootstrapped peers actually connected via event hooks.
• Add these bootstrapped addresses as explicit peers.