Advanced dataset filtering

[coreation]

The front-end needs a more advanced filtering system for the next release. This means a front-end and back-end enhancement:

• [x] Front-end ajax calls to the filter back-end, in Vue components
• [x] Back-end take into account the different filters and apply i18n
• [x] Provide a paging functionality in the Vue component

[coreation]

• [x] Provide facetted counts
• [x] Save relevant facet data to the facets table when a dataset is created/update