## 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.
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