feat(manifest): make explicit Gecko Android compatibility

Until now we marked manually in the Mozilla Add-ons Store that the
extension is Android compatible. However, recently the store requires
extensions to make it explicit in the manifest,[1] so this CL adds the
appropriate key to indicate it.

[1]: https://blog.mozilla.org/addons/2023/10/05/changes-to-android-extension-signing/

Change-Id: I0af32dffcdd2c54caed7ea6100e2138006fa6a8c

templates/manifest.gjson

@@ -173,6 +173,9 @@
     "gecko": {
       "id": "twpowertools@avm99963.com",
       "strict_min_version": "102.0"
+    },
+    "gecko_android": {
+      "strict_min_version": "102.0"
     }
   },
 #endif