feat: extract headless workflow engine

tests/fixtures/bpmn/process.bpmn

@@ -0,0 +1,50 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<bpmn:definitions
+  xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL"
+  xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI"
+  xmlns:dc="http://www.omg.org/spec/DD/20100524/DC"
+  xmlns:di="http://www.omg.org/spec/DD/20100524/DI"
+  xmlns:govoplan="urn:govoplan:workflow:fixture-extension"
+  id="Definitions_Process"
+  targetNamespace="urn:govoplan:workflow:fixtures">
+  <bpmn:process id="Process_Linear" isExecutable="true">
+    <bpmn:extensionElements>
+      <govoplan:fixture revision="1">
+        <govoplan:note>Preserve this extension exactly.</govoplan:note>
+      </govoplan:fixture>
+    </bpmn:extensionElements>
+    <bpmn:startEvent id="Start_1">
+      <bpmn:outgoing>Flow_1</bpmn:outgoing>
+    </bpmn:startEvent>
+    <bpmn:userTask id="Task_1" name="Review">
+      <bpmn:incoming>Flow_1</bpmn:incoming>
+      <bpmn:outgoing>Flow_2</bpmn:outgoing>
+    </bpmn:userTask>
+    <bpmn:endEvent id="End_1">
+      <bpmn:incoming>Flow_2</bpmn:incoming>
+    </bpmn:endEvent>
+    <bpmn:sequenceFlow id="Flow_1" sourceRef="Start_1" targetRef="Task_1" />
+    <bpmn:sequenceFlow id="Flow_2" sourceRef="Task_1" targetRef="End_1" />
+  </bpmn:process>
+  <bpmndi:BPMNDiagram id="Diagram_1">
+    <bpmndi:BPMNPlane id="Plane_1" bpmnElement="Process_Linear">
+      <bpmndi:BPMNShape id="Shape_Start_1" bpmnElement="Start_1">
+        <dc:Bounds x="80" y="112" width="36" height="36" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="Shape_Task_1" bpmnElement="Task_1">
+        <dc:Bounds x="220" y="90" width="100" height="80" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNShape id="Shape_End_1" bpmnElement="End_1">
+        <dc:Bounds x="430" y="112" width="36" height="36" />
+      </bpmndi:BPMNShape>
+      <bpmndi:BPMNEdge id="Edge_Flow_1" bpmnElement="Flow_1">
+        <di:waypoint x="116" y="130" />
+        <di:waypoint x="220" y="130" />
+      </bpmndi:BPMNEdge>
+      <bpmndi:BPMNEdge id="Edge_Flow_2" bpmnElement="Flow_2">
+        <di:waypoint x="320" y="130" />
+        <di:waypoint x="430" y="130" />
+      </bpmndi:BPMNEdge>
+    </bpmndi:BPMNPlane>
+  </bpmndi:BPMNDiagram>
+</bpmn:definitions>