Input parameters are not removed from XML when morphing Service Task into Receive Task

[barmac]

Describe the Bug

Although input parameters are no longer accessible in the properties panel when Service Task is morphed into Receive Task, they are still present in the XML.

Steps to Reproduce

1. Create a Service Task
2. Add input parameters

Task's XML at this point looks like this:

    <bpmn:serviceTask id="Activity_07bz79w">
      <bpmn:extensionElements>
        <zeebe:ioMapping>
          <zeebe:input source="= source" target="target" />
        </zeebe:ioMapping>
      </bpmn:extensionElements>
    </bpmn:serviceTask>

3. Morph into Receive Task
4. Check XML:

    <bpmn:receiveTask id="Activity_07bz79w">
      <bpmn:extensionElements>
        <zeebe:ioMapping>
          <zeebe:input source="= source" target="target" />
        </zeebe:ioMapping>
      </bpmn:extensionElements>
    </bpmn:receiveTask>

Extension elements should be removed so it should look like this:

    <bpmn:receiveTask id="Activity_07bz79w" />

Expected Behavior

Input parameters should be removed. User can still recover them via undo.

Environment

• OS: MacOS 10.15.6
• Zeebe Modeler Version: 0.10.0-rc.0

[MaxTru]

The same issue applies for calledElement when morphing from a callActivity to something else.

As @barmac explained to me, we need to fix this in zeebe-bpmn-moddle, compare https://github.com/camunda/camunda-bpmn-moddle/blob/master/lib/extension.js#L27

[azeghers]

What we need:

• [x] Tests for copy behavior
• [x] ZeebeModdleExtension that implements a canCopyProperties
• [ ] Integrate it in the Zeebe Modeler

[MaxTru]

Closed by #274