[DX-3593] [DX-3617] [DX-3620] ci: fix ios build and ui tests

[nattb8]

Summary

• Updated the sample iOS app build to allow arbitrary loads, enabling connection to AltTester when using BrowserStack Local.
• Updated the BrowserStack configuration to auto-accept alerts and use pytest.
• Moved iOS-related test files to the ios/ directory.
• Commented out other iOS tests for now, as they rely on Python unittest functions/annotations, which do not work well with BrowserStack + Appium. These will be addressed in a future PR.
• Fixed the Xcode path in the iOS build script to handle scenarios where multiple Xcode versions are installed on the macOS machine.