Support processVariables defined in *eventDefinitions

[MaxTru]

Is your feature request related to a problem? Please describe

ProcessVariables defined as part of *eventDefinitions are not yet extracted by the library. This shall be added.

Describe the solution you'd like Extract processVariables from:

• bpmn:errorEventDefinitions -> camunda:errorCodeVariable and camunda:errorMessageVariable
  • Example: <bpmn:errorEventDefinition id="ErrorEventDefinition_0dv020s" errorRef="Error_1cttq7o" camunda:errorCodeVariable="varA" camunda:errorMessageVariable="varB" />
  • This shall result in two process variables extracted: varA and varB
• bpmn:escalationEventDefinition -> camunda:escalationCodeVariable
  • Example: <bpmn:escalationEventDefinition id="EscalationEventDefinition_0dbxygj" escalationRef="Escalation_1qli310" camunda:escalationCodeVariable="varC" />
  • This shall result in one process variable extracted: varC

Describe alternatives you've considered

None

Additional context

Was highlighted by @ingorichtsmeier (thanks!)