This method has a similar purpose as "guesstoremote" but is for use when
the channel's database ID is known. It produces the private key that can
spend the to_remote output of the peer's commitment transaction. It
assumes the channel was negotiated with option_static_remotekey unless
the optional per-commitment point argument is provided.
Changelog-Added: hsmtool has a new `derivetoremote` method.
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