Can't create a Queue UI plugin that works for queue names with "/"

Problem/Motivation

For the queue_unique module, we added a way to prefix a queue name like "queue_unique/node_updates" and override the core queue factory to give you a queue_unique instance instead of a default instance when you ask for that from the factory. https://www.drupal.org/project/queue_unique/issues/3301657 →

Unfortunately, if I try to make a trivial subclass of Drupal\queue_ui\Plugin\QueueUI\DatabaseQueue to be able to inspect those queue items, I get an exception on the queue listing page /admin/config/system/queue-ui

Symfony\Component\Routing\Exception\InvalidParameterException: Parameter "queueName" for route "queue_ui.inspect" must match "[^/]++" ("queue_unique/node_updates" given) to generate a corresponding URL. in Drupal\Core\Routing\UrlGenerator->doGenerate() (line 203 of core/lib/Drupal/Core/Routing/UrlGenerator.php).
Drupal\Core\Routing\UrlGenerator->getInternalPathFromRoute('queue_ui.inspect', Object, Array, Array) (Line: 291)
Drupal\Core\Routing\UrlGenerator->generateFromRoute('queue_ui.inspect', Array, Array, 1) (Line: 105)
Drupal\Core\Render\MetadataBubblingUrlGenerator->generateFromRoute('queue_ui.inspect', Array, Array, 1) (Line: 765)
Drupal\Core\Url->toString(1) (Line: 182)
Drupal\Core\Utility\LinkGenerator->generate(Object, Object) (Line: 95)
Drupal\Core\Render\Element\Link::preRenderLink(Array)
...

Steps to reproduce

Proposed resolution

using rawurlencode() on the queue name before passing as a route parameter doesn't work, unfortunately.

So, find another way to encode any "/" in the queue name (or url-safe base64 encode the whole name) and then decode in \Drupal\queue_ui\Form\InspectForm::buildForm()

Remaining tasks

User interface changes

none

API changes

none