Revisit design of filter badges

[joverlee521]

Context

Initially brought up by @jameshadfield in #1924 (comment)

Probably beyond this PR, but this makes me think about some improvements to the filter badges - they haven't seen any development since they were first introduced and filtering has become a much bigger part of workflows since then.

It'd be nice to show the title not the key when hovering, and even nicer if we could somehow render this in the badge itself, as a badge simply showing "true" isn't very intuitive. We already do both of these in the sidebar

Also brought up by @trvrb in #1924 (comment)

1. The "filtered to true" is a bit strange and should be clearer.

The box in the side bar is properly clear:

Description

We should revisit the design of the filter badges displayed at the top of the page. We can try displaying the filter title along with the filter value in the badges, but be aware of long titles and values. The badges can already look a bit clunky when there are multiple filters with long field values.

(We already try to avoid long author lists in builds for bad display reasons, but just using this as example.)