Move module_filter (or its functionality) in core for D8

Problem/Motivation

We seemed to be going this way in #538904: D8UX: Redesign Modules Page. Eventually (if this idea is accepted) we'll break that issue in smaller ones, so expect this issue here to perhaps move back 'n' forth between here and the core issue queue.

The idea was debated and usage stats of module_filter were questioned when it came to claiming that vertical tabs in the Modules page is of great acceptance. More on this here: #1356426: Clarify in the project's page that people not fond of the vertical tabs should use instantfilter instead.

Proposed resolution

...as per issue title. Here's the issue filed against core: #1348692: Vertical Tabs for the Modules page

Remaining tasks

• Move it in core ;) ...or at least base our effort on code from this project so we don't reinvent the wheel.
• Separate the searching/filtering part in another issue (@TODO - possible candidate is Instant filter)

User interface changes

• Categories converted from the current collapsible fieldsets to either vertical tabs or a set of checkboxes (a-la solr search)
• Display only basic information (the enable/disable checkbox, module name, version, update status) and hide/move extra info (module description, action links, requirement/dependency list) in a collapsed by default fieldset.
• Provide a way to optionally/selectively short alphabetically or group by category.

Note: we are not solid on all of these yet - mostly ideas and mockups from #538904: D8UX: Redesign Modules Page:

post #144 by jstoller
post #157 by Xano
post #175 by eigentor

API changes

???

Original report by Frando

I recently read in another issue that you plan to update the module for Drupal 7. I worked on a core patch to provide a searchable module page with vertical tabs that is based on #323112: Vertical Tabs. Please see #396478: Searchable modules page for more details, screenshots and patch - would be great to join forces. What the patch mostly needs is some attention and UX reviews.