Add Form Binding Properties

[philippfromme]

In order to support binding to form files as described in #2295 we need to add new properties to this extension.

New User Task Properties

• camunda:formRef (maps to id property of the form)
• camunda:formRefBinding (latest or version)
• camunda:version (maps to an internal version property set by the engine)

Example

<bpmn:userTask
  id="Activity_1"
  camunda:formRef="formId"
  camunda:formRefBinding="version">
</bpmn:userTask>

or

<bpmn:userTask
  id="Activity_1"
  camunda:formRef="latest">
</bpmn:userTask>

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Child of camunda/camunda-modeler#2295