Allow users to "boomerang" a thread to show up in their inbox again after some time

[braid-sync]

A task for new Braid contributors.

Goal:
Add the "boomerang" feature that's common in various email clients, where you can click a button to hide an email from your inbox and have it re-show-up after some time. In Braid, this would involve boomeranging a thread instead. (If there's a better term than boomerang for it, by all means, change the terminology).
You can show the option to boomerang in the thread menu (which shows on-hover of the close button). For now, a preset boomerang time (of, let's say, 48 hours) is sufficient.

Notes:

• This should be implemented as a new module
• braid.stars is a good reference for how to write modules
• you will likely need to create a job to check for threads to re-open; braid.core.api/register-daily-job! exists, but you may need to add an hourly version
• braid.core.api/register-thread-control! can be used to add a button to the thread menu