Animated hint to show that filters can be scrolled to the left when first viewed

[damianmoore]

Some users on all devices are not realising they can scroll horizontally to get to more filters. We should show an animation the first time they view the filters, scrolling about 200px and then back again to the start. This animation should last about 1 second.

Use useLocalStorageState hook as used elsewhere to store whether this animation has been shown as we never want to show it again on that device.

The animation/transition itself can be performed through CSS with keyframes triggered by adding a className from React

Note that users on small screens will not see these filters by default. For these users the animation would only display once they have expanded the search area for the first time.

[GyanP]

I have completed the task and pushed on branch "228-auto-scroll".

[damianmoore]

Merged as of edb77fd