Undoing an adoption into a Skipped book leaves it Wanted #2885

Found while fixing #2879 (PR #2883), which now suggests Skipped and Imported books when adopting a file. Adoption does not record the book's previous status, so Undo on an adoption into a Skipped book restores it as Wanted (and unmonitored) rather than Skipped. Picking a Skipped book through the library search could already do this; suggesting Skipped books makes it more likely. Fix: record the prior status on the adoption so Undo can restore it (likely a new column on the adoption record).