Add entries for Transcode Settings in Dev Options

Transcode Settings screen would be used to enable/disable transcoding for all apps, and select a list of apps to be skipped from transcoding.
UI screenshot of Transcode Settings screen: https://screenshot.googleplex.com/4bpbZdM6vbhdw5u

Design doc reference for native transcoding: go/seamless-transcoding

Test: Manual
Bug: 169547037
Change-Id: I2762da7535f441a85ae5ad01df3d6a328502c962
diff --git a/stats/enums/app/settings_enums.proto b/stats/enums/app/settings_enums.proto
index d46da87..a2a7649 100644
--- a/stats/enums/app/settings_enums.proto
+++ b/stats/enums/app/settings_enums.proto
@@ -2786,4 +2786,9 @@
     // CATEGORY: SETTINGS
     // OS: S
     LOCATION_TIME_ZONE_DETECTION = 1854;
+
+    // OPEN: Settings > Developer options > Media transcode settings
+    // CATEGORY: SETTINGS
+    // OS: S
+    TRANSCODE_SETTINGS = 1855;
 }