staking miner: spawn separate task for each block (#4716)

* staking miner: use config for emergency solution

Fixes #4678

* bump jsonrpsee

* run `monitor_cmd_for` until the connection is closed

* new tokio task for submit_and_watch xt

* re-use header subscription

* update jsonrpsee + simplify code

* revert polkadot runtime changes

* fix grumbles

* Update utils/staking-miner/src/monitor.rs

* grumbles: fix logs + nits