fix --from overriding annex-ignore

Make git-annex get/copy/move --from foo override configuration of
remote.foo.annex-ignore, as documented.

This already worked for remotes supporting hasKeyCheap. For others though,
git-annex copy --from foo would silently not do anything, while
git-annex copy --to foo would use the annex-ignored remote.

Also improved the annex-ignore docs, to reflect that `git-annex get`
without --from will skip using annex-ignored remotes, for example.

Sponsored-by: Dartmouth College's DANDI project

Command/Sync.hs

@@ -897,7 +897,7 @@ seekSyncContent o rs currbranch = do
 syncFile :: SyncOptions -> Either (Maybe (Bloom Key)) (Key -> Annex ()) -> [Remote] -> AssociatedFile -> Key -> Annex Bool
 syncFile o ebloom rs af k = do
 	inhere <- inAnnex k
-	locs <- map Remote.uuid <$> Remote.keyPossibilities k
+	locs <- map Remote.uuid <$> Remote.keyPossibilities (Remote.IncludeIgnored False) k
 	let (have, lack) = partition (\r -> Remote.uuid r `elem` locs) rs
 
 	got <- anyM id =<< handleget have inhere