build: enable ProGuard and R8 code optimization

Author: hugofnm

app.json

@@ -204,6 +204,15 @@
           },
           "imageWidth": 200
         }
+      ],
+      [
+        "expo-build-properties",
+        {
+          "android": {
+            "enableMinifyInReleaseBuilds": true,
+            "enableShrinkResourcesInReleaseBuilds": true
+          }
+        }
       ]
     ],
     "experiments": {

package-lock.json

@@ -20,6 +20,7 @@
     "expo": "^57.0.0",
     "expo-alternate-app-icons": "^8.0.0",
     "expo-application": "~57.0.3",
+    "expo-build-properties": "~57.0.17",
     "expo-constants": "~57.0.8",
     "expo-crypto": "~57.0.3",
     "expo-dev-client": "~57.0.19",