deprecate iOS .xcodeproj (#25583)

Summary:
Pull Request resolved: #25583

We now use CocoaPods for better maintainability.

Reviewed By: hramos

Differential Revision: D16193719

fbshipit-source-id: faf6c7920cf2b37754f78b419c26c377da6e58e2

Author: fkgozali

.circleci/config.yml

@@ -376,6 +376,10 @@ jobs:
 
       - run: pod setup
 
+      - run:
+          name: Generate RNTesterPods Workspace
+          command: pushd RNTester && pod install --verbose && popd
+
       - run:
           name: Run Detox iOS End-to-End Tests
           command: yarn run build-ios-e2e && yarn run test-ios-e2e