Possibility of using offchain-worker to implement relay worker?

[hackfisher]

[wuminzhe]

https://www.youtube.com/watch?v=Fm_x84v8uF0
https://github.com/jimmychu0807/substrate-offchain-pricefetch

https://gnunicorn.github.io/substrate-offchain-cb/

[hackfisher]

Duplicate with #289