Send contact requests

[adriacidre]

Problem

At the moment there is no way to get other users name, this is needed for status-go-bots so they can add names to the users interacting on public channels

Implementation

This development involves some research and even the interaction is done through NewContactRequest and a ConfirmedContactRequest we have to check how do they exactly work.

In terms of the api would be nice to have a helper to manage contact requests asynchronous message publication and subscription like:

var john sdk.Contact
err := Request(contactAddress, &john)

And for bots a general option to always accept incoming contact requests.

Acceptance Criteria

As a SDK user i can send and manage contact requests to any random user address, and retrieve that specific contact information in case it's confirmed

Notes

Reference docs:

• new protocol
• how to sniff app messages
• contact management