Multiple triggers support

[joseconstela]

As a user, I can add multiple triggers to a workflow.

This needs to cover the following:

• On the sidebar, I can add both tasks (as of now) but also triggers (this are services that have the property trigger to to true.
• When a service is triggered, it must search for all triggers in all workflows, not just for one. Example for the endpoint service:

  const flow = Flows.findOne({
    status: 'enabled',
    'trigger.type': 'endpoint',
    'trigger.event': 'called',
    'trigger.config.endpoint': uuid
  })

should be something like

  const flow = Flows.find({
    status: 'enabled',
    'triggers.type': 'endpoint',
    'triggers.event': 'called',
    'triggers.config.endpoint': uuid
  })

• The queue engine must be updated, because a workflow execution might not trigger all tasks available in a workflow, but only those tasks connected the the triggered task.