Forums: Add ability to sort unresolved threads

[TacoVerdo]

At this moment, someone doing support for a plugin on the repository can either choose to show threads ordered by activity (e.g. ​https://wordpress.org/support/plugin/wordpress-seo/active/) or filter out the unresolved topics (e.g. ​https://wordpress.org/support/plugin/wordpress-seo/unresolved/).

However, there is no way to sort all unresolved topics by their latest activity.

For plugins with an active support forum, this hinders their ability to respond to the oldest pending requests first, as it means continuously sifting through the list manually to find the unresolved thread waiting for the longest for a reply.

Therefore, I'd like to see more sorting options for the forum threads, with the main one being the 'last post', but ideally also the 'voice count' and 'reply count'.

[TacoVerdo]

Screenshot of the headers of the plugin forums

[mrfoxtalbot]

This ticket came up during the weekly bug scrub. We decided it made sense to bump this up to see how viable it would be. Any thoughts on what the name of the endpoint should be? /active-recent? I cannot think of anything more elegant than that @TacoVerdo :P

Also, in case someone lands this ticket and is unaware of it, there is ​a brilliant user script by @clorith that will highlight topics based on their status.