Improve performance retrieving datasets by investigation

Time measured to get datasets by investigationId should not exceed 0.2s. This is possible just retrieving the datasets with no params or information associated.

https://confluence.esrf.fr/display/DATAPOLWK/Performance+comparison+retrieving+datasets+from+ICAT

This issue address to parametrize the endpoint to allow fast retrieval of datasets. This is specially important when doing lazy loading.