Figure out how to post the worker metrics on-chain

[dzhelezov]

The worker reward for each epoch depends on:

• The amount of data processed
• The amount of data stored (counted as Gb * sec)
• The number of previous epochs it is online
• The number of pings received
• The amount of SQD delegated to the worker

We need to figure out:

• how to make this information available on-chain in order to calculated the worker reward for each epoch
• how to make sure that the provided information is valid

[dzhelezov]

One possible solution/direction: worker received signed responses from the router acknowledging that the submitted logs with pings were received. If the worker can submit the data on-chain to challenge the data submitted by the router if it is not sound.

[dzhelezov]

streamr.network <- decentralized messaging with the option to keep history

[vanruch]

Researched streamr, managed to test stream creation, write/read. One small problem is they only have JS lib, so for a worker written in Rust, we'll need to have a streamr-broker process going, like described here, which may make worker setup a bit trickier

[dzhelezov]

Actually our workers are written in Python (see archive-py repo)