Add tests for the current behaviour of --cross

[Gedochao]

This adds missing, rudimentary tests for the workings of the (still experimental) --cross command line option with various Scala CLI sub-commands which support it.

• run cross-compiles against provided versions, but only runs the first of them, as per run should actually run each of the cross-compiled configurations with --cross #3590
• test runs tests for each of the cross-compiled versions
• package cross-compiles against provided versions, but only packages for the first of them, as per package should actually package each of the cross-compiled configurations with --cross #3591
• publish and publish local actually cross-publish for each of the provided versions.

Adding these tests to prevent changing these behaviours by accident, as I did in #3538