Add Fastlane and GitHub Actions for CI

[r3econ]

This commit introduces Fastlane for building the iOS project and integrates it with GitHub Actions.

• A Gemfile is added with fastlane as a dependency.
• A fastlane/Fastfile is created with a build lane that uses gym to build the Spacequest scheme.
• A GitHub Actions workflow in .github/workflows/main.yml is set up to:
  • Trigger on every push.
  • Checkout the code.
  • Set up Ruby and Bundler.
  • Install gems.
  • Run bundle exec fastlane build to build the application.

This will automate the build process for every push to the repository.