[pilot] add xros as valid option for pilot upload

[demonnic]

Checklist

• I've run bundle exec rspec from the root directory to see all new and existing tests pass
• I've followed the fastlane code style and run bundle exec rubocop -a to ensure the code style is valid
• I see several green ci/circleci builds in the "All checks have passed" section of my PR (connect CircleCI to GitHub if not)
• I've read the Contribution Guidelines
• I've updated the documentation if necessary.
• I've added or updated relevant unit tests.

Motivation and Context

The Apple Vision Pro headset officially releases this Friday, and currently the process I use for uploading apps to Apple is blocked because xros is not considered a supported platform by fastlane pilot

Description

This change adds xros as a valid option everywhere appletvos is mentioned for pilot, and also adjusts the specs. Prompted by the discussion #21802

I updated our resigning service to use my updated local copy of fastlane and was able to fastlane pilot upload our vision pro ipa with these changes.

Once this PR is ironed out I'm likely to take a look at adding it to the deliver in the hopes of maybe getting a release out ahead of or in line with the vision pro launch if at all possible.

Testing Steps

The command ultimately used to test the upload was bundle exec fastlane pilot upload --api-key-path <REDACTED> --skip_waiting_for_build_processing --team_id <REDACTED> --ipa <PATH/TO/IPA>

[lacostej]

LGTM