Add flag to "zoo kcl export" to enforce deterministic output

[maruel]

https://github.com/KittyCAD/kcl-samples/blob/main/.github/workflows/output-from-kcl-samples.yml#L31 runs sed to try to trim the date out and hope for determinism.
Instead, there should be a flag to force the output to be deterministic.

This enable users to refactor kcl code and ensure that the result stays the same. As a project using kcl grows, the ability to safely refactor will become critical in large teams.

This may not always be possible for all formats, and that's useful insight in itself as the tool can assert this explicitly, instead of hoping for the best.