AI Export progress should be tracked by model name

Currently, Continuous export retrieves model ids from Insight. The system should rely on model name, so the export status can be known for 3rd party users who is not aware of Nuxeo internals.

Requirements:

• Review ContinuousExportListener and its logic. It should:
  • pull all models by datasource
  • initiate export for each one 
  • store export id and model name for further tracking