chanrestore: add new file to house chanbackup interface implementations
chanrestore: add new file to house chanbackup interface implementations

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.

aakselrod/lnd,aakselrod/lnd,LightningNetwork/lnd,LightningNetwork/lnd