Change Research menu entry to Datasets

...p/core/components/main/side-menu/side-menu.component.html

...esults/results-tab-scope/results-tab-scope.component.html

src/app/datasets/services/dataset-research.service.ts

src/app/shared/variables.ts

src/i18n/messages.en.xlf

src/i18n/messages.fr.xlf