be stricter about rejecting invalid configurations for remotes

This is a first step toward that goal, using the ProposedAccepted type
in RemoteConfig lets initremote/enableremote reject bad parameters that
were passed in a remote's configuration, while avoiding enableremote
rejecting bad parameters that have already been stored in remote.log

This does not eliminate every place where a remote config is parsed and a
default value is used if the parse false. But, I did fix several
things that expected foo=yes/no and so confusingly accepted foo=true but
treated it like foo=no. There are still some fields that are parsed with
yesNo but not not checked when initializing a remote, and there are other
fields that are parsed in other ways and not checked when initializing a
remote.

This also lays groundwork for rejecting unknown/typoed config keys.

Remote/Helper/Chunked.hs

@@ -21,6 +21,7 @@ import Annex.Common
 import Utility.DataUnits
 import Types.StoreRetrieve
 import Types.Remote
+import Types.ProposedAccepted
 import Logs.Chunk
 import Utility.Metered
 import Crypto (EncKey)
@@ -51,16 +52,16 @@ noChunks _ = False
 getChunkConfig :: RemoteConfig -> ChunkConfig
 getChunkConfig m =
 	case M.lookup chunksizeField m of
-		Nothing -> case M.lookup "chunk" m of
+		Nothing -> case M.lookup (Accepted "chunk") m of
 			Nothing -> NoChunks
-			Just v -> readsz UnpaddedChunks v "chunk"
-		Just v -> readsz LegacyChunks v chunksizeField
+			Just v -> readsz UnpaddedChunks (fromProposedAccepted v) (Accepted "chunk")
+		Just v -> readsz LegacyChunks (fromProposedAccepted v) chunksizeField
   where
 	readsz c v f = case readSize dataUnits v of
 		Just size
 			| size == 0 -> NoChunks
 			| size > 0 -> c (fromInteger size)
-		_ -> giveup $ "bad configuration " ++ f ++ "=" ++ v
+		_ -> giveup $ "bad configuration " ++ fromProposedAccepted f ++ "=" ++ v
 
 -- An infinite stream of chunk keys, starting from chunk 1.
 newtype ChunkKeyStream = ChunkKeyStream [Key]