WIP: use StakeTableV2

[sveitser]

• Verify signatures on new events in GCL.
• Deploy StakeTableV2
• Allow CLI to register and update keys with both versions of the contract for backwards compat.

Notes

• The tests are not all using V2 yet.
• The staking-cli probably doesn't yet have full compatibility due to event and error decoding.

Todo

• Decide at what layer we reject un-authenticated events. I think it would be best to not put them into the database at all. Currently I think what I implemented would actually store them first and only reject them when we are building the stake table. Since those events will be super rare, maybe it also doesn't matter.
• Run at least some of the tests against V1 and V2 of the contract.

---

• To see the specific tasks where the Asana app for GitHub is being used, see below:
  • https://app.asana.com/0/0/1210174253354699
  • https://app.asana.com/0/0/1210174253354700