offchain worker: pass rpc params from node into worker

[aramikm]

Problem

Currently we have hardcoded the local rpc node to http://localhost:9944 since we could not pass in the node params via custom extension due to an existing bug on substrate that is fixed on 1.3 release.

Acceptence criterea

• add new extension to pass in rpc url and port into offchain worker
• use that value inside offchain worker

Details

https://stackoverflow.com/questions/77516271/how-do-i-register-a-custom-extension-for-offchain-workers
offchain_custom_extension.patch

This is blocked due to a bug until the upgrade to v1.3