Template support for UserTask definitions

[ftreede]

Problem you would like to solve

I want to create element templates for User Tasks with external task forms (served by a custom task application)

Right now, this is not possible since I cannot specify properties for zeebe:formDefinition or zeebe:assignmentDefinition via the template.

Also, setting a template on a user task right now has it default to the Job Worker implementation; there is no way to force it to use the new Zeebe User Tasks.

Proposed solution

A functionality to map to the zeebe:userTask, zeebe:formDefinition, zeebe:assignmentDefinition and zeebe:taskSchedule in the same way we can currently control zeebe:taskDefinition.

It would then be used in the template like this:

{
    "type": "Hidden",
    "binding": {
        "type": "zeebe:userTask",
    }
},
{
    "type": "Hidden",
    "value": "MyExternalForm",
    "binding": {
        "type": "zeebe:formDefinition",
        "property": "externalReference"
    }
},
{
    "label": "Assignee",
    "description": "Assignee for user task",
    "type": "String",
    "binding": {
        "type": "zeebe:assignmentDefinition",
        "property": "assignee"
    }
}

Alternatives considered

It is possible to show the default assignment attributes by setting "entriesVisible": true in the template. However, this will also result in showing other properties we do not want to expose. Also, it requires users to input settings like the form key manually, which is what we want to avoid by providing a template.

Additional context

No response