Multi data source search

[khaledk2]

This PR introduces the basis for searching the data from multi-data sources.
The current status:

• It can restore the database from a backup.
• It queries the databases and pushes the data to the Elatsicsearch indices
• The unit test has been modified to restore and index two OMERO databases and then run all tests inside the test units.
• There is a new endpoint to return the available data sources i.e./api/v1/resources/data_resources/.
• It can return the results from all sources or limit the search to a specific data source
• It has been deployed successfully on pilot-es1-omeroreadwrite

The indexing process (getting the data into the elasticsearch indices) supports querying the OMERO databases and then indexing the returned data.
We should account for cases in which we do not have access to the databases or backups.

• The searchengine supports indexing the data from CSV files.
  • This feature has not been used for a long time and needs to be maintained and fixed to cope with modifications.
• In addition, we should support accepting the data directly from JSON or maybe calling API to retrieve the data and then index it.

[joshmoore]

Long-term I assume this is an issue. I wonder to what extent we couldn't try omero-test-infra for the github tests and then do something larger on our own systems.