Tihis commit is implementing a 2-phase commit between
the signer the node and the peer.
The main reason for this is that everybody must agree on the lock,
otherwise one of them will want N signatures (on the splice candidates),
and another will produce only 1 signature.
check_outpoint is the "prepare" for the signer, and lock_outpoint is the
"commit". if check_outpoint returns true, lock_outpoint must not fail.
Link: https://github.com/ElementsProject/lightning/issues/6722
Suggested-by: @devrandom
Co-Developed-by: Ken Sedgwick <ken@bonsai.com>
Signed-off-by: Vincenzo Palazzo <vincenzopalazzodev@gmail.com>
44798e298c