Ability to change burn_fee_cap and satoshis_per_byte in config without restarting

[yknl]

Currently the node needs to be restarted in order to change the burn fee and Bitcoin network fee rate. Having the ability to change these config params without restarting would help with mining consistently.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically closed. Please reopen if needed.

[jcnelson]

Closing in favor of #3256