[Advanced Search][Enhancement] Make the advanced search filter section sticky when scrolling

[pierbrisson]

Current behavior

When scrolling through advanced search results, the left hand filter section doesn't follow the scroll, hence leaving the user uninformed of what filters have been applied to his search. This behavior coupled with the fact that the search header isn't sticky either (cf. issue #830) prevents the user from seeing the filters he selected.

Expected behavior

Make the left hand filter section present at all times when scrolling through the search results.

[sgoretti]

👍

[AdrienViala]

utiliser le scrollSpy qui est aussi sticky pour reprendre le comportement @BaptisteCoppere