Accessed only/ burn errors

[lydiagarms]

This PR fixes several errors:

1. An error when it is detected that a variable is set to zero i.e. burned. Previously, it was checking that the owner binding was set to zero, which wasn't always giving the correct result.
2. An error for a function where there are no new nullifiers but we do use checkNullifiers, i.e. we access secret variables and so need to make sure we are using the most up to date commitment by a nullifier doesn't exist in the nullifier list. The length of the inputs during proof verification in the Shield Contract were wrong in this case.
3. In orchestration, we do a check to make sure the new leaves have been successfully added on chain at the end. However, if there are no new commitments, we should not include this check or an error will be returned incorrectly. Previously things were being marked as not burned only, i.e. the check included, even when there were no new commitments.

[jtcoolen]

Thanks!

[github-actions]

🎉 This PR is included in version 1.10.4 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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