Replace BadgerDB with own key-value storage implementation

[cedricfung]

The transaction implementation in BadgerDB is critical for the Kernel consensus, and we can't make the core consensus implementation rely on such a large external project which we have no deep understanding.

[crossle]

How about leveldb https://github.com/syndtr/goleveldb?

[cedricfung]

We should make our own DB.

[cedricfung]

https://github.com/tidwall/buntdb

[crossle]

https://github.com/torquem-ch/mdbx-go

[cedricfung]

We got this panic from BadgerDB 4.2.0 already

panic: Base level can't be zero.