feat: On chain ledger

[mudler]

As part of #345 we have decided to go with our on-chain ledger rather then using another third party ledger.

Describe the solution you'd like

The key takeaways are:

• we have our own ledger that can store a limited set of data in the on-chain ledger. The ledger is implemented similarly to what EdgeVPN uses.
• The ledger can be used to store a CID (content addressable ID) to reference a data that is carried over with the ledger. that for instance can be used to store big files or content that doesn't fit the ledger (see also Spike: On chain ledger #345 (comment) )
• The ledger can be written only by trusted nodes, but can be read by all nodes of the network
• For development, we can also point to an IPFS CID that is then pinned by the oracle nodes. That would allow us to quickly iterate in the short term while we develop a CID system inside our own protocol.

This card is about wrapping up the esperimental PR work in #350 and have it merged in the repository.

Describe alternatives you've considered
Using an external blockchain as a ledger (see discussions in #345)

Additional context
N/A

Acceptance criteria

• Spike: On chain ledger #345 #350 is wrapped up and merged in the codebase