Enable dataset queries in EVE framework

[TomasKulhanek]

Query for existing annotation related to dataset and dataset elements
This could be achieved by:

1. Presuming [dataset_element_url] == [dataset url]/[dataset file]. Filtering annotation by target.source using regex to filter dataset url starting with specified string - dataset elements:
   https://b2note.bsc.es/api/annotations?where={%22target.source%22:{%22$regex%22:%20%22^https://trng-b2share.eudat.eu/api/files/44f3fc75-3f68-42c2-b537-ae0917ebcb44/.*%22}}

2. Presuming dataset element annotation share same target.id. Filtering annotation by target.id - same value shared among dataset elements:
   https://b2note.bsc.es/api/annotations?where={%22target.id%22:%22http://hdl.handle.net/0000/810f3882fa0a4196aa9fd080de5f71c7%22}

[TomasKulhanek]

$regex and filtering by target.id is disabled by default.
Query contains operators banned in MONGO_QUERY_BLACKLIST" - thus regex should be enabled in eve config https://docs.python-eve.org/en/stable/config.html
"filter on 'target.id' not allowed" - again needs to be enabled in eve config

After enabling filter and regex in query

• Option 1 'target.source':{"$regex":"..."} returns all annotation where the source url string starts with dataset url
• Option 2 'target.id':... seems not working - null is returned