Implement integration tests that confirm specific Xcode versions work

[cgrindel]

The project aims to define a matrix of Bazel versions and Xcode versions that work with rules_xcodeproj. The integration tests should exercise a basic set of functionality for each supported combination. As a general rule, the project will support the latest Xcode version, the previous release and the last major release. As of the writing of this issue, those versions are:

• Latest: 13.3
• Previous: 13.2.1
• Previous Major: 13.0

NOTE: The supported Bazel versions are already defined in //:bazel_versions.yml.

• [ ] Create a file/macro that defines the supported Xcode versions.
• [ ] Update the ios_app integration test to execute the supported combinations.

[brentleyjones]

We aren't using https://github.com/bazel-contrib/rules_bazel_integration_test anymore, but we should still do this, just at the BuildBuddy Workflows level. We should also confirm bazel and rules_apple/rules_swift version support.

[brentleyjones]

I don't think this should block the 1.0 release, so I've changed the milestone. Please tell me if you believe differently.