Improve filter chip display in narrow containers / viewports

[jameskoster]

In #59696 the display of individual chips can be finessed.

But we still need to figure out the display of many filters in narrow containers / viewports. It's not a huge problem right now because the existing data views only have <=2 filters.

However, things like Posts or Media (#55238) can have many filter options, and this experience isn't ideal:

Let's explore how to better display many chips in the filter UI.

[jameskoster]

The simplest thing to try here would be horizontal scrolling with a slightly different button appearance / layout:

horizontal.mp4

• Add filter and Reset buttons fixed in position on the right
• Add filter and Reset become icon buttons
• Filter chips scroll horizontally

Some other things we might try to save space:

• Remove the inline x buttons
• Reduce chip size and internal padding

There are usability trade-offs to this though, so perhaps worth looking at separately.

[jameskoster]

Another option would be to restrict display to X number of chips, and hide the others behind a + x more link:

[jasmussen]

The horizontal scrolling is a common practice on mobile devices and scales well. If paired with the scrollbar mixin, it could work well and potentially be simple to implement, at least as a starting point.

[SaxonF]

Something else we tried early on is if on mobile or list view, condense filters down into dropdown. We'd have an indicator "1" on filter icon. Relates a little to previous discussions about hiding view filters by default.

[SaxonF]

Horizontal scrolling is also nice though and an improvement over what we have.