trivial: move CachingOptions out of content.Manager, where it's not needed (#775)

* trivial: move CachingOptions out of content.Manager, where it's not needed

* trivial: removed newManagerWithOptions which was the same as NewManager

also moved one-time initialization to newReadManager()

cli/command_cache_set.go

@@ -19,7 +19,7 @@ var (
 )
 
 func runCacheSetCommand(ctx context.Context, rep *repo.DirectRepository) error {
-	opts := rep.Content.CachingOptions.CloneOrDefault()
+	opts := rep.Cache.CloneOrDefault()
 
 	changed := 0