Make admin's list_filter choices collapsable

[Greg McCoy]

I made a change to my site to add a toggle collapse on the filters in the admin page. Is this something we'd like in Django by default?

[Tim Graham]

Sure, it was proposed in wiki:DjangoDesign#Collapsefiltersinchangelistsidebar:

Filter options take of a lot of vertical space in the changelist sidebar. This makes it difficult to use fields with lots of options as filters, or to use more than a few fields as filters. This could be solved by adding an option to display filters with more than a specified number of options as a select element instead of in a list. (WM)

#21183 is a related ticket about collapsing the entire sidebar.

[Tim Graham]

​PR (without tests or documentation updates -- some screenshots need to be updated, for example).

[Mariusz Felisiak]

Related to the #21183 which is about toggling specific filters, not the entire filter block. I'm not sure we need both 🤔.

[Marcelo Galigniana]

Here I add the 2nd approach ​PR using ​summary/details elements

[Marcelo Galigniana]

The disclosure element was re-styled and persistence logic added!

[Mariusz Felisiak <felisiak.mariusz@…>]

In 27aa7035:

Fixed #27471 -- Made admin's filter choices collapsable.

[GitHub <noreply@…>]

In 4a72da71:

Refs #27471 -- Made admin's filter choice arrows use cursor pointers.