filter out control characters in warning messages

Converted warning and similar to use StringContainingQuotedPath. Most
warnings are static strings, some do refer to filepaths that need to be
quoted, and others don't need quoting.

Note that, since quote filters out control characters of even
UnquotedString, this makes all warnings safe, even when an attacker
sneaks in a control character in some other way.

When json is being output, no quoting is done, since json gets its own
quoting.

This does, as a side effect, make warning messages in json output not
be indented. The indentation is only needed to offset warning messages
underneath the display of the file they apply to, so that's ok.

Sponsored-by: Brett Eisenberg on Patreon

Annex/Content.hs

@@ -6,6 +6,7 @@
  -}
 
 {-# LANGUAGE CPP #-}
+{-# LANGUAGE OverloadedStrings #-}
 
 module Annex.Content (
 	inAnnex,
@@ -447,7 +448,7 @@ checkSecureHashes' :: Key -> Annex Bool
 checkSecureHashes' key = checkSecureHashes key >>= \case
 	Nothing -> return True
 	Just msg -> do
-		warning $ msg ++ "to annex objects"
+		warning $ UnquotedString $ msg ++ "to annex objects"
 		return False
 
 data LinkAnnexResult = LinkAnnexOk | LinkAnnexFailed | LinkAnnexNoop
@@ -760,9 +761,10 @@ downloadUrl listfailedurls k p iv urls file uo =
 	go [] [] = return False
 	go [] errs@((_, err):_) = do
 		if listfailedurls
-			then warning $ unlines $ flip map errs $ \(u, err') ->
-				u ++ " " ++ err'
-			else warning err
+			then warning $ UnquotedString $
+				unlines $ flip map errs $ \(u, err') ->
+					u ++ " " ++ err'
+			else warning $ UnquotedString err
 		return False
 
 {- Copies a key's content, when present, to a temp file.