Prior to this commit, taproot channels had a bug:
- If a disconnect happened before peer.AddNewChannel was called,
then the subsequent reconnect would call peer.AddNewChannel and
attempt the ChannelReestablish dance.
- peer.AddNewChannel would call NewLightningChannel with
populated nonce ChannelOpts. This in turn would call
InitRemoteMusigNonces which would create a new musig pair session
and set the channel's pendingVerificationNonce to nil.
- During the reestablish dance, ProcessChanSyncMsg would be called.
This would also call InitRemoteMusigNonces, except it would fail
since pendingVerificationNonce was set to nil in the previous
invocation.
To fix this, we add a new functional option to signal to the init logic
that it doesn't need to call InitRemoteMusigNonces in in
ProcessChanSyncMsg.