This is a mix of both the
hammond-downloader re-work and the way the gtk+ client handles downloads.
Create the mockup
Switch from the custom downloader to a downloader crate Refactor a bunch of stuff and tests to the new crate Create the headerbar icon and Popover Show headerbar icon only when there are active downloads
Create a download manager that will "Own" and manage the download threads.
EpisodeWidgetaccording to the mockuup
Assert downloading stuff works
Assert download manager functions properly Assert the download button is only shown when needed