Port 66dbb59aa1 to glitch-soc

The feature to pin column could hide the rightmost column, which is
specified with children property of ColumnsArea.

The user is likely to see the column when the property changed, so scroll
the area in such cases.

* added notification cleaning drawer

* bugfix

* fully implemented set operations for notif cleaning

* i18n for notif cleaning drawer & improved logic slightly. Also added a confirm dialog

* - notif dismiss "overlay" now shoves the notif aside to avoid overlap
- added focus ring to header buttons
- removed notif overlay entirely from DOM if mode is disabled

* removed comment

* CSS tuning - inconsistent division lines fix

* chore(yarn): Install detect-passive-events

* fix(column): Use passive listener

This PR adds a new notification cleaning mode, super perfectly tuned for accessibility, and removes the previous notification cleaning functionality as it's now redundant.

* w.i.p. notif clearing mode

* Better CSS for selected notification and shorter text if Stretch is off

* wip for rebase ~

* all working in notif clearing mode, except the actual removal

* bulk delete route for piggo

* cleaning + refactor. endpoint gives 422 for some reason

* formatting

* use the right route

* fix broken destroy_multiple

* load more notifs after succ cleaning

* satisfy eslint

* Removed CSS for the old notif delete button

* Tabindex=0 is mandatory

In order to make it possible to tab to this element you must have tab index = 0. Removing this violates WCAG and makes it impossible to use the interface without good eyesight and a mouse. So nobody with certain mobility impairments, vision impairments, or brain injuries would be able to use this feature if you don't have tabindex=0

* Corrected aria-label

Previous label implied a different behavior from what actually happens

* aria role localization & made the overlay behave like a checkbox

* checkboxes css and better contrast

* color tuning for the notif overlay

* fanceh checkboxes etc and nice backgrounds

* SHUT UP TRAVIS

ref https://tc39.github.io/proposal-decorators/

* Allow mounting arbitrary columns

* Refactor column headers, allow pinning/unpinning and moving columns around

* Collapse animation

* Re-introduce scroll to top

* Save column settings properly, do not display pin options in
single-column view, do not display collapse icon if there is
nothing to collapse

* Fix one instance of public timeline being closed closing the stream
Fix back buttons inconsistently sending you back to / even if history exists

* Getting started displays links to columns that are not mounted