Ask for delete confirmation when selecting multiple jobs

[dragondgold]

Would be nice if, when selecting multiple discarded/cancelled/completed jobs, the UI asked you to confirm deletion instead of simply deleting everything as a safety measure.

Side note, would it be useful for river to have a Trash so manually deleted jobs go there (different table) for a configurable amount of time before being permanently deleted?

[bgentry]

@dragondgold hi there, thanks for the report! I added a modal confirmation in #546 for delete on the bulk/list view and on the single job page since this action is destructive and irreversible. It'll go out in the next release.