In this commit, we convert the server's Start/Stop methods to use the
sync.Once. We do this in order to fix concurrency issues that would
allow certain queries to be sent to the server before it has actually
fully start up. Before this commit, we would set started to 1 at the
very top of the method, allowing certain queries to pass before the rest
of the daemon was had started up.
In order to fix this issue, we've converted the server to using a
sync.Once, and two new atomic variables for clients to query to see if
the server has fully started up, or is in the process of stopping.
In this commit, we move the location where we restore the channel status
to within the `RestoreChannelShells` method itself. Before this commit,
we attempted to use `ApplyChanStatus` which creates a DB transaction and
relies on a fully populated channel state, which in the restoration
case, we don't yet have.
The `openChannelShell` method now includes the new config information
within the open channel shells. Additionally, we now properly re-derive
all keys from our local chan config so they're useable immediately in
the channel state machine.
We extend the `chanDBRestorer.RestoreChansFromSingles` method to also
add the new channels to the chain arbitrator once they've been restored
on disk. We do this in order to ensure that we catch the channel closure
on chain once the DLP protocol beings.
