first pass at assistant knowing about export remotes

Split exportRemotes out from syncDataRemotes; the parts of the assistant
that upload keys and drop keys from remotes don't apply to exports,
because those operations are not supported.

Some parts of the assistant and webapp do operate on both
syncDataRemotes and exportRemotes. Particularly when downloading from
either of them. Added a downloadRemotes that combines both.

With this, the assistant should download from exports, but it won't yet
upload changes to them.

This commit was sponsored by Fernando Jimenez on Patreon.

Assistant/DaemonStatus.hs

@@ -20,6 +20,7 @@ import Logs.TimeStamp
 import qualified Remote
 import qualified Types.Remote as Remote
 import Config.DynamicConfig
+import Annex.Export
 
 import Control.Concurrent.STM
 import System.Posix.Types
@@ -53,15 +54,18 @@ calcSyncRemotes = do
 	alive <- trustExclude DeadTrusted (map Remote.uuid rs)
 	let good r = Remote.uuid r `elem` alive
 	let syncable = filter good rs
-	syncdata <- filterM (not <$$> liftIO . getDynamicConfig . remoteAnnexIgnore . Remote.gitconfig) $
+	contentremotes <- filterM (not <$$> liftIO . getDynamicConfig . remoteAnnexIgnore . Remote.gitconfig) $
 		filter (\r -> Remote.uuid r /= NoUUID) $
 		filter (not . Remote.isXMPPRemote) syncable
+	let (exportremotes, dataremotes) = partition (exportTree . Remote.config) contentremotes
 
 	return $ \dstatus -> dstatus
 		{ syncRemotes = syncable
 		, syncGitRemotes = filter Remote.gitSyncableRemote syncable
-		, syncDataRemotes = syncdata
-		, syncingToCloudRemote = any iscloud syncdata
+		, syncDataRemotes = dataremotes
+		, exportRemotes = exportremotes
+		, downloadRemotes = contentremotes
+		, syncingToCloudRemote = any iscloud contentremotes
 		}
   where
 	iscloud r = not (Remote.readonly r) && Remote.availability r == Remote.GloballyAvailable