## Issue Addressed
Closes#1365
## Proposed Changes
Dial peers in the `cached_enrs` who aren't connected, aren't banned and satisfy the subnet predicate before making a subnet discovery query.
## Issue Addressed
#1378
## Proposed Changes
Boot node reuses code from beacon_node to initialize network config. This also enables using the network directory to store/load the enr and the private key.
## Additional Info
Note that before this PR the port cli arguments were off (the argument was named `enr-port` but used as `boot-node-enr-port`).
Therefore as port always the cli port argument was used (for both enr and listening). Now the enr-port argument can be used to overwrite the listening port as the public port others should connect to.
Last but not least note, that this restructuring reuses `ethlibp2p::NetworkConfig` that has many more options than the ones used in the boot node. For example the network config has an own `discv5_config` field that gets never used in the boot node and instead another `Discv5Config` gets created later in the boot node process.
Co-authored-by: Age Manning <Age@AgeManning.com>
## Issue Addressed
N/A
## Proposed Changes
Refactor attestation service to send out requests to find peers for subnets as soon as we get attestation duties.
Earlier, we had much more involved logic to send the discovery requests to the discovery service only 6 slots before the attestation slot. Now that discovery is much smarter with grouped queries, the complexity in attestation service can be reduced considerably.
Co-authored-by: Age Manning <Age@AgeManning.com>
## Issue Addressed
Resolves#1489
## Proposed Changes
- Change starting metadata seq num to 0 according to the [spec](https://github.com/ethereum/eth2.0-specs/blob/dev/specs/phase0/p2p-interface.md#metadata).
- Remove metadata field from `NetworkGlobals`
- Persist metadata to disk on every update
- Load metadata seq number from disk on restart
- Persist enr to disk on update to ensure enr sequence number increments are persisted as well.
## Additional info
Since we modified starting metadata seq num to 0 from 1, we might still see `Invalid Sequence number provided` like in #1489 from prysm nodes if they have our metadata cached.
## Issue Addressed
#1384
Only catch, as currently implemented, when dialing the multiaddr nodes, there is no way to ask the peer manager if they are already connected or dialing
## Issue Addressed
#1483
## Proposed Changes
Upgrades the log to a critical if a listener fails. We are able to listen on many interfaces so a single instance is not critical. We should however gracefully shutdown the client if we have no listeners, although the client can still function solely on outgoing connections.
For now a critical is raised and I leave #1494 for more sophisticated handling of this.
This also updates discv5 to handle errors of binding to a UDP socket such that lighthouse is now able to handle them.
