- Allow access to contentDB from portal wire protocol
- Use this to do the db.get in `handleFindContent` directly
- Use this to check the `contentKeys` list in `handleOffer`
* Change History content key to us SSZ Union and adjust tests
* Change slot to byteBE instead of LE
This is currently not specified in the Portal network
specifications, but we are using already BE for the actual content
key, so change it also here to remain consistent.
* Rename FindNode to FindNodes as per spec
* Use consistently lower case starting camelCase for consts
Style guide nep1 allows for both CamelCase and camelCase for
consts, but we seem to use more often camelCase. Using this now
consistently.
* Change some procs to func
* Add SSZ Unions through case objects
* Add connection id content response test and improve other test vectors
* Implement content keys and ids for state network as per spec
Content keys case object is used so that it can be serialized and
deserialized as an SSZ Union.
* Let message Union in Portal wire protocol start at 0 as per new spec
Kim De Mey