Add Swift Testing

[KaitoMuraoka]

Since XCTest is already included, I’d like Swift Testing to be added as well.

日本語

XCTestは追加されているので、Swift Testing も追加していただきたいです。

Swift Testing URL: https://github.com/swiftlang/swift-testing

[kishikawakatsumi]

Thank you for suggestion.

If I add Swift Testing, how do I run it? Is there a way to run Swift Testing with a specific file? I am wondering if it is necessary to define a package and create a test target in order to run the test. @KaitoMuraoka