vis: Figure out good UX for caching the test filter
The new vis (!33 (closed)) comes with a text field in the navbar that is used for filtering grids on test names and by default cached that.
The UX it presented though is too confusing (value stays there forever, no button to clear it, not easy to spot), especially for people coming without the implementation knowledge so the caching got disabled as of b0980dc3.
- Add a (x) to reset the value
- Make persistence optional (checkbox?)
- make filter more visible (either by putting red "filter" in the front or by blinking it?)