Add support for script tasks in NodeJS

[cosmin-harangus]

The script task element should allow users to execute scripts or files from any other programming language.
The initial version of the Hashiru BPMN engine should allow support the following programming languages:

• Nodejs(required)
• Golang(coming soon)
• Elixir(coming soon)

Bellow is an example BPMN representation of the script task in camunda:

<bpmn:scriptTask id="Task_1ymg9vn" name="CHECK USER EXISTS" scriptFormat="nodejs" camunda:resultVariable="user" camunda:resource="scripts/user/get_by_username.js">
  <bpmn:extensionElements>
    <camunda:inputOutput>
      <camunda:inputParameter name="username" />
      <camunda:inputParameter name="password" />
      <camunda:outputParameter name="user">user</camunda:outputParameter>
    </camunda:inputOutput>
  </bpmn:extensionElements>
  <bpmn:incoming>SequenceFlow_0u2ggjm</bpmn:incoming>
  <bpmn:outgoing>SequenceFlow_1i6wlcd</bpmn:outgoing>
  <bpmn:property id="Property_04h1su1" name="__targetRef_placeholder" />
  <bpmn:dataInputAssociation id="DataInputAssociation_08cossw">
    <bpmn:sourceRef>DataStoreReference_0o13718</bpmn:sourceRef>
    <bpmn:targetRef>Property_04h1su1</bpmn:targetRef>
  </bpmn:dataInputAssociation>
</bpmn:scriptTask>