fix: Fix DRM workaround for Tizen and Xbox with avc3 boxes (shaka-project#3625)

The workaround previously only matched avc1 boxes.  This adds avc3 to the workaround, fixing content that uses this box on Tizen and Xbox.

Author: david-hm-morgan

lib/media/content_workarounds.js

@@ -75,6 +75,12 @@ shaka.media.ContentWorkarounds = class {
             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
           });
         })
+        .fullBox('avc3', (box) => {
+          boxesToModify.push({
+            box,
+            newType: ContentWorkarounds.BOX_TYPE_ENCV_,
+          });
+        })
         .fullBox('ec-3', (box) => {
           boxesToModify.push({
             box,