Improve awkward dialog title

Please never use the word “dialog” in a dialog’s title.
It’s obvious.
This string has led to confused translations.

Change-Id: Id55d45a48630e5f3d3f01d4eee87240f9907a803

avmedia/source/viewer/mediawindow.src

@@ -26,7 +26,7 @@ String AVMEDIA_STR_INSERTMEDIA_DLG
 
 String AVMEDIA_STR_OPENMEDIA_DLG
 {
-    Text[en-US] = "Open Audio and Video Dialog";
+    Text[en-US] = "Open Audio or Video";
 };
 
 String AVMEDIA_STR_ALL_MEDIAFILES