Persist ASDB for charon, copy it during an edit, check it on boot

[OisinKyne]

🎯 Problem to be solved

Real time edits without downtime

🛠️ Proposed solution

• Approved design doc: link
• Core team consensus on the proposed solution

Describe the solution to be implemented

🧪 Tests

• We can detect an absence of data in the ASDB (e.g. the last record i have is for slot X, and we're now further, and this validator is still active, that must mean its been scheduled and i just don't know if I participated or not
• Manually tested on core team/canary/test clusters
• Manually tested on local compose simnet

Additional Acceptance Criteria

We have a BN in front of us, maybe its not too painful a startup request to ask the BN if the active pubkeys have attested in the current and last epoch? (to detect if the rest of the DV is keeping the validator online that you weren't aware of) I know this was a feature we turned off in an ongoing basis, but might be worth it best-effort at startup?

To be finished in a design doc