* Make stop functions wait for completion before return.
* Implement graceful shutdown.
* Shutdown rpc and metric servers if enabled.
* Move metrics and rpc servers out of PortalNode.
- Add basic validation for LC bootstrap gossip, validating either
by trusted block root (only 1) when not synced, or by comparing
with the header of the latest finality update when synced.
- Update portal_bridge beacon to also gossip bootstraps into the
network on each end of epoch.
* Add nph check to fluffy CI lint
* Add a section on nph usage in the fluffy.guide
* Update copyright years for altered files
* Avoid chained methods formatting style in db code
* Update nph in CI to v0.5
* Remove leftover commented import
* Move comment to avoid nph turning complex list into simple list (nph bug)
* Update nph in CI to v0.5.1
* Formatting fluffy with nph v0.5.1