Check changed data in participant import preview entries

Describe the enhacement
A referenced participant on import can also have his data updated. To avoid unwanted overwritings it's important to show that the imported data is different than the current participant's data. For that, a different state for entries is needed.

How To Reproduce

1. Create participant in Meeting_1
2. Create Meeting_2
3. Change to Meeting_2
4. Import CSV file with any of that participant's data changed
5. Participant is referenced but the updated data in the cell is not shown as updated

Payload from client (handle_request)
[{"action":"participant.json_upload","data":[{"data":[{"first_name":"Max","last_name":"Musterhuman","email":"maxi@example.com","member_number":"12345678","structure_level":"Berlin","groups":"Delegates, Staff","number":"D001","vote_weight":"1","gender":"diverse","pronoun":"they","default_password":"333","is_active":"1","is_physical_person":"1","comment":"asdsadsa"},{"first_name":"Jo","last_name":"Nesbø","email":"jonesbo@email.com"},{"first_name":"Bjørnstjerne","last_name":"Bjørnson","email":"bojostene@email.com"}],"meeting_id":2}]}]

Response from backend
{"status_code": 200, "success": true, "message": "Actions handled successfully", "results": [[{"id": 2049, "headers": [{"property": "title", "type": "string", "is_object": true}, {"property": "first_name", "type": "string", "is_object": true}, {"property": "last_name", "type": "string", "is_object": true}, {"property": "is_active", "type": "boolean", "is_object": true}, {"property": "is_physical_person", "type": "boolean", "is_object": true}, {"property": "default_password", "type": "string", "is_object": true}, {"property": "email", "type": "string", "is_object": true}, {"property": "username", "type": "string", "is_object": true}, {"property": "gender", "type": "string", "is_object": true}, {"property": "pronoun", "type": "string", "is_object": true}, {"property": "saml_id", "type": "string", "is_object": true}, {"property": "member_number", "type": "string", "is_object": true}, {"property": "home_committee", "type": "string", "is_object": true}, {"property": "external", "type": "boolean", "is_object": true}, {"property": "structure_level", "type": "string", "is_object": true, "is_list": true}, {"property": "number", "type": "string", "is_object": true}, {"property": "vote_weight", "type": "decimal", "is_object": true}, {"property": "comment", "type": "string", "is_object": true}, {"property": "is_present", "type": "boolean", "is_object": true}, {"property": "groups", "type": "string", "is_object": true, "is_list": true}, {"property": "locked_out", "type": "boolean", "is_object": true}], "rows": [{"state": "done", "messages": [], "data": {"first_name": {"value": "Max", "info": "done"}, "last_name": {"value": "Musterhuman", "info": "done"}, "email": {"info": "done", "value": "maxi@example.com"}, "member_number": {"value": "12345678", "info": "done", "id": 25}, "number": {"value": "D001", "info": "done"}, "vote_weight": {"value": "1.000000", "info": "done"}, "pronoun": {"value": "they", "info": "done"}, "default_password": {"value": "333", "info": "done"}, "is_active": {"value": true, "info": "done"}, "is_physical_person": {"value": true, "info": "done"}, "comment": {"value": "asdsadsa", "info": "done"}, "id": 25, "username": {"value": "MaxMusterhuman", "info": "done"}, "gender": {"info": "done", "value": "diverse", "id": 3}, "groups": [{"value": "Delegates", "info": "done", "id": 9}, {"value": "Staff", "info": "done", "id": 10}], "structure_level": [{"value": "Berlin", "info": "new"}]}}, {"state": "new", "messages": [], "data": {"first_name": {"value": "Jo", "info": "done"}, "last_name": {"value": "Nesb\u00f8", "info": "done"}, "email": {"info": "done", "value": "jonesbo@email.com"}, "username": {"value": "JoNesb\u00f8", "info": "generated"}, "default_password": {"value": "3PX7Zpda4A", "info": "generated"}, "groups": [{"value": "Default", "info": "generated", "id": 7}]}}, {"state": "new", "messages": [], "data": {"first_name": {"value": "Bj\u00f8rnstjerne", "info": "done"}, "last_name": {"value": "Bj\u00f8rnson", "info": "done"}, "email": {"info": "done", "value": "bojostene@email.com"}, "username": {"value": "Bj\u00f8rnstjerneBj\u00f8rnson", "info": "generated"}, "default_password": {"value": "hjFDDZxXsi", "info": "generated"}, "groups": [{"value": "Default", "info": "generated", "id": 7}]}}], "statistics": [{"name": "total", "value": 3}, {"name": "created", "value": 2}, {"name": "updated", "value": 1}, {"name": "error", "value": 0}, {"name": "warning", "value": 0}, {"name": "structure levels created", "value": 1}, {"name": "groups created", "value": 0}], "state": "done"}]]}

Expected behavior
The info field shows updated instead of done when the imported value doesn't match with the user's current information. Should return: "email": {"info": "updated", "value": "maxi@example.com"}

Start at the participant.json_upload action and its handle_request path, then trace how referenced participant fields are compared and how each entry's info value is assigned. Reproduce the import with changed participant data and add or update a regression test for the preview response. Done means differing imported values return info "updated" while unchanged values remain "done".