Fix operation 'Context.GetTaskNames' so that it retrieves tasks using a custom document type

Operation Context.GetTaskNames uses NXQL query Select * from TaskDoc where ecm:mixinType IN ('RoutingTask') AND ecm:isCheckedInVersion = 0 AND ecm:currentLifeCycleState = 'opened' to retrieve the opened tasks. The problem is it mentions document type TaskDoc (just use Document instead) so tasks using a custom document type are not retrieved.

How to reproduce:

• in Studio Modeler, create a document type named NXP-25955_TaskDoc:
  • Extends Document
  • Category: Miscellaneous
  • LifeCycle: task
  • facet Document is a task checked
  • facet Document is a core routing task checked
• copy workflow SerialDocumentReview to a new workflow named NXP-25955_SerialDocumentReview
• in Definition tab of workflow NXP-25955_SerialDocumentReview, change property label to NXP-25955_SerialDocumentReview
• in the graph editor of workflow NXP-25955_SerialDocumentReview, edit node with title wf.serialDocumentReview.chooseParticipants, go to tab General:
  • change property Task Document type to NXP-25955_TaskDoc
  • change property Title to NXP-25955_SerialDocumentReview Choose Participants
• deploy Studio project to a Nuxeo Platform instance
• log in the JSF UI
• create a file document named File1
• start a NXP-25955_SerialDocumentReview workflow on the document File1
• Navigate to HOME > Workflows
• click on the down arrow of suggestion widget Task name to filter the content view

Expected result: suggestion widget Task Name suggests tasks [Serial document review] Choose Participants and [NXP-25955_SerialDocumentReview] NXP-25955_SerialDocumentReview Choose Participants
Actual result: suggestion widget Task Name only suggests task [Serial document review] Choose Participants

While we are at changing the code, why not use a page provider so that it would be much easier to change the NXQL query and change the backend to which the query is sent (database, elasticsearch, ...).