#24865 Added associated_entity_type parameter to task and step

When creating a step or task folder, toolkit needs to figure out which parent folder to associate the step or task with. This is currently done by looking up the folder tree and picking the first shotgun folder that is found. However, For complex folder setups, where for example you want to have a structure with `Sequence > Shot > Department > Step`, this approach won't work, because it will find Department rather than the desired Shot level. 

This pull request adds an optional `associated_entity_type` parameter to the folder configs which allows a user to explicitly specify the type of the parent folder to bind the task or step to. In the example above, we would set `associated_entity_type: Shot` in order to tell the system not to associate the step with the department object but instead (correctly) with the Shot object.