Execution integration

[Zacholme7]

Issue Addressed

• Execution layer  #20
• Sync Smart Contract Data #23

Proposed Changes

This PR tracks the integration of the execution layer into anchor. The process can be thought of as the following:

1. Fetch all relevant contract events from the chain
2. Perform verification and parsing on the events and then store them into the database.
3. If we are caught up to the chain and following along, determine if some action needs to be taken in response to the event.

Additional Info

Types and the database are being worked on alongside this as they all mesh together.

[jimmygchen]

Nice! great progress @Zacholme7 👏

I know this is WIP, but I thought some early feedback after a quick read might be helpful.

I've added some comments and questions above, and here are a few more:

• Would be useful to add more logging, both for informative and debug purpose (e.g. sync progress, live events received, fetch or processing errors etc)
• I'd love to see some unit & integration tests where it make sense. It doesn't have to be this PR, but I wanted to mention it since we recently started adding tests in the validator client, and it's been a little painful. Adding tests while the codebase is fresh can make things a bit more testable by design and save some headaches later.

I'm not familiar with SSV, so my comments are mostly generic, but I'd like to catch up and review this again later when it's ready.

Overall it's very tidy and nice to read, great job 👍

[jking-aus]

check with ssv on reason for 8 block follow distance

[jking-aus]

reviewed in call on 14/1 -- nice work zac good to get this one finished