Additional changes:
* Update fuzz crate to match ChannelManager's new API
* Update lightning-net-tokio library to match ChannelManager's new ChannelMonitor Deref API
* Update tests to match ChannelManager's new ChannelMonitor Deref API
Because filter_block takes a and returns a list of s , we must add a lifetime to the ChainWatchInterface, which bubbles up in a lot of places. These places include adding a lifetime to the Node struct, which causes a lot of rearranging tests so that variables don't go out of scope before the Node that owns them does.
Adding this struct will allow us to remove the circular reference
between ChainListeners and the ChainWatchInterface, because it
separates out the responsibility of notifying listeners about new
blocks from the responsibility of storing and retrieving watched
transactions.
This includes the purpose of this PR, which is to remove the circular reference created by ChainListeners self-adding themselves to their ChainWatchInterface's `listeners` field.
