HTTP task should have an option to *not* throw an error on a 404

### The feature, motivation and pitch

When writing idempotent workflows, we often will do a GET on a resource to see if it exists and branch based on the result - if we get a 404 we create and continue with the new object and if we get a 200 we just proceed with the existing object.

This is a very common automation pattern, and we should support it there.

### Alternatives

_No response_

### Additional context

_No response_

Start by locating the HTTP task implementation and its handling of 404 responses, then read the surrounding tests or task documentation if available. The change is done when an option lets an idempotent workflow treat a 404 as a usable result while preserving the existing error behavior by default.

Written by the indexing model from the issue text.