Add media constraints for arbitrary file types

Fixes #6573
// FREEBIE

src/org/thoughtcrime/securesms/util/MediaUtil.java

@@ -164,6 +164,10 @@ public class MediaUtil {
     return !TextUtils.isEmpty(contentType) && contentType.trim().startsWith("video/");
   }
 
+  public static boolean isFile(Attachment attachment) {
+    return !isImage(attachment) && !isAudio(attachment) && !isVideo(attachment);
+  }
+
   public static boolean hasVideoThumbnail(Uri uri) {
     Log.w(TAG, "Checking: " + uri);