[Devicelab] Add physical device integration tests for iOS Universal Links (Deep Linking) #189200

Currently, there are no integration tests in Flutter CI that verify authentic iOS Universal Link (Deep Link) routing on physical devices. We manually have to test deep link behavior when OS updates roll out, which leaves us highly vulnerable to regressions.

Rough Idea

We already host an AASA file at https://flutter-dashboard.appspot.com/.well-known/apple-app-site-association which whitelists com.google.experimental0.dev under the Team ID.

We can utilize this existing infrastructure to build a Devicelab test on a physical Mac_ios bot:

Create a new Devicelab task on mac_ios bot and include apple_signing CIPD dependency

dependencies: >
  [
    {"dependency": "apple_signing", "version": "version:to_2026"}
  ]

add a script to dev/devicelab/bin/tasks/ to update the PRODUCT_BUNDLE_IDENTIFIER to com.google.experimental0.dev, and inject an Entitlements file containing the applinks:flutter-dashboard.appspot.com Associated Domain.

For execution we can install the app with xcrun devicectl device install app --device <id> --source <path> and launch via the universal link xcrun devicectl device process launch --device <id> --url https://flutter-dashboard.appspot.com/invalid_route