[LN Decentralization E] Integrate `PendingTree` in the compliance engine

[durkmurder]

Context

Once PendingTree supports both certified and pending blocks integrate it in the compliance engine and change how the block processing logic is implemented. Specifically the new workflow should look something like this:

1. Receive new block from the committee
2. Check if block needs processing(dedup, already processed, have another block for this view)
3. Check if leader is equivocating.
4. Validate proposal
5. Add proposal to the PendingTree.
6. If proposal connects to the finalized state, extend the block state.