[Improvement] Add logic for multiple field collection fields

[lukmzig]

Changes in this pull request

Resolves issue when having multiple allowed field collection items in the class definition field. The field collection items can contain fields with same name which will result in overriding of the mapping.
The fields should be nested based on the field collection item names (type).

e.g
Error: "Handling "Pimcore\Bundle\GenericDataIndexBundle\Message\IndexUpdateQueueMessage" failed: handleIndexQueueEntry failed! Error: Bulk operation produced errors: {"took":0,"errors":true,"items":[{"index":{"_index":"pimcore_data-object_filterdefinition-odd","_id":"563","status":400,"error":{"type":"mapper_parsing_exception","reason":"failed to parse field [standard_fields.filters.preSelect] of type [text] in document with id '563'. Preview of field's value: '{document=[], asset=[], object=[]}'","caused_by":{"type":"illegal_state_exception","reason":"Can't get text on a START_OBJECT at 1:1110"}}}}]}" ["class" => "Pimcore\Bundle\GenericDataIndexBundle\Message\IndexUpdateQueueMessage","retryCount" => 3,"delay" => 4000,"error" => "Handling

preSelect get overriden by text field since its an input field in FilterInputField and in the FilterCategory it is a relation

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[markus-moser]

Didn't test it but in general it LGTM