* Always prefer the non-finalized tip in ChainTipSender
This significantly simplifies the internal implementation of ChainTipSender.
Also make the methods and types a bit more generic.
* Update ChainTipSender with blocks, not heights
Also fix a bug where queued non-finalized blocks would clear the chain tip.
* Provide a best tip hash in ChainTip receivers
* Skip finalized blocks once the non-finalized state is active
* Add tip hash and NoChainTip tests
* Remove a redundant finalized tip update
* Skip `None` updates to the finalized tip
The finalized and non-finalized tips never update to `None`
once they have added at least one block.
* Stop committing finalized queued blocks if there is an error
Also return the highest committed queued block.
Co-authored-by: Janito Vaqueiro Ferreira Filho <janito.vff@gmail.com>