Refactor so client state watches L1 and trigger CL genesis only after horizon block reached

[delbonis]

The genesis block isn't going to be hardcoded in production, we'll set a horizon L1 block and switch to it as the oldest block we can fetch from and using operator nominations from before then to initialize the genesis state. This means that the client state has to take inputs from these blocks and do things with them before we actually initialize the chainstate genesis stuff. There should be a DoGenesis sync action that the CSM can produce and the worker carries out when we've decided that genesis is happening. This splits apart some of the genesis init work so that we can start running the L1 reader and run the CSM worker without fully starting the chain sync stuff (it would still be there, but just be idle waiting for a real state to start working off of).

Related #123
This should close #123