In this commit, we break the old `launchResolvers` into two steps - step
one is to launch the resolvers synchronously, and step two is to
actually waiting for the resolvers to be resolved. This is critical as
in the following commit we will require the resolvers to be launched at
the same blockbeat when a force close event is sent by the chain watcher.
We will use this and its following commits to break the original
`Resolve` methods into two parts - the first part is moved to a new
method `Launch`, which handles sending a sweep request to the sweeper.
The second part remains in `Resolve`, which is mainly waiting for a
spending tx.
Breach resolver currently doesn't do anything in its `Launch` since the
sweeping of justice outputs are not handled by the sweeper yet.
This `immediate` flag was added as a hack so during a restart, the
pending resolvers would offer the inputs to the sweeper and ask it to
sweep them immediately. This is no longer need due to `blockbeat`, as
now during restart, a block is always sent to all subsystems via the
flow `ChainArb` -> `ChannelArb` -> resolvers -> sweeper. Thus, when
there are pending inputs offered, they will be processed by the sweeper
immediately.
