Import my favorites to my queue

[marleighnorton]

We've got favoriting, which is a quick and easy way to remind yourself what you're interested in, and then queues, which let you actually sign up for stuff. A feature to let folks add their favorites to their queues seems good. Could also help with some of the use cases being discussed in #10084

Currently thinking something like:

• A button on the queue that says "Import my favorites"
• When clicked, make a list of the user's favorite events
• Randomize the order of favorite events
• For each event:
• • If event is already in queue, skip it
• • Otherwise, randomize the buckets
• • • For each bucket, add it to the end of the queue

This should keep all instances for a given event grouped together, but otherwise randomize things so the algorithm doesn't privilege certain events. And if the event is already in your queue, even if not all the buckets selected, it can be assumed you already processed it in some manner and we can ignore it.

[marleighnorton]

For extra points, we could do a confirmation dialogue that says something like:

The following events will be added to the end of your queue:

• [List of events]

These events are already in your queue, so will be skipped:

• [List of events]

And special messages for the "You have not marked any events as Favorites" and "All events marked as Favorites are already in your queue" cases.