client(consensus/grandpa): implement grandpaDb and environment types

[jimjbrettj]

Changes

• add an interface to represent grandpa DB interactions. After reviewing their auxDB impl, I don't think we need to implement all of it right now and believe we are ok having simple db interactions.
• add logic in auxDB that is relevant to our implementation as well as tests
• create all the environment types needed for our db impl and test them
• add ability to decode custom vdts within maps and custom vdts to scale package

Tests

go test -tags integration github.com/ChainSafe/gossamer

Issues

Primary Reviewer

@EclesioMeloJunior

[EclesioMeloJunior]

The keys and values are always bytes, I see that you are receiving strings, what I would suggest is to:

type databaseKeyValue [2][]byte

type AuxStore interface {
    Insert(toInsert []databaseKeyValue, toDelete [][]byte)
    Get(key []byte) []byte
}

ex: https://go.dev/play/p/C6oQRS_-Ett

[timwu20]

great work!

resolved