Prepare mobile Android 0.0.50

Cut from 5e70014da8, the same commit that shipped iOS 0.0.50, so the
Android build matches what iOS users received. versionCode 16 already
shipped as 0.0.48, so it moves to 17.

mobile/app.json

@@ -2,7 +2,7 @@
   "expo": {
     "name": "Orca",
     "slug": "orca-mobile",
-    "version": "0.0.48",
+    "version": "0.0.50",
     "orientation": "default",
     "icon": "./assets/icon.png",
     "userInterfaceStyle": "automatic",
@@ -75,7 +75,7 @@
       "allowBackup": false,
       "permissions": ["RECORD_AUDIO", "MODIFY_AUDIO_SETTINGS"],
       "package": "com.stably.orca.mobile",
-      "versionCode": 16,
+      "versionCode": 17,
       "googleServicesFile": "./google-services.json"
     },
     "plugins": [