feat: Ability to easily compare versions using #toArtifactVersion

[KristianOellegaard]

If you want to verify that your automatic pipeline does not deploy an old version because it is accidentally pushed to the docker repo

eg

#toArtifactVersion(execution.trigger.tag.replace("v", "")) >= #toArtifactVersion(#stage("Find Artifacts From Resource (Manifest)").manifest.spec.template.spec.containers[0].image.split(":")[1].replace("v", ""))

[spinnakerbot]

The following commits need their title changed:

• 4050f32: Add support for DefaultArtifactVersion to allow easy comparison in pipeline expressions

• c3fd821: Fix return type

• 8b03e4c: Fixed missing semi colon and correct return type

• 309c6c6: Added test

Please format your commit title into the form:

<type>(<scope>): <subject>, e.g. fix(kubernetes): address NPE in status check

This allows us to easily generate changelogs & determine semantic version numbers when cutting releases. You can read more about commit conventions here.

[jasonmcintosh]

SO this tries to translate the expression to a string. What's interesting is I DON'T think it's ever actually USED. Transform MAP is used. Ignoring that, you can use this but this I believe returns a boolean which it tries to cast as a string and then fails. Can switch to a transformMap (which is what's REALLY used) OR maybe add a .toString() on the results. I'd be inclined to do the map based test via a "transformMap(Map.of("test", testInput)...).get("test"). " kinda test.