How to find the active scheme of a project/workspace

Similar to the problem I've described on [stackoverflow](https://stackoverflow.com/questions/76918735/how-to-detect-active-scheme-of-an-xcode-project-workspace-from-command-line)

There're only somethings like:

```rb
Xcodeproj::Workspace.new_from_xcworkspace("My.xcworkspace").schemes
Xcodeproj::Project.schemes("My.xcodeproj")
```

What I want is: `Xcodeproj::Project.active_scheme("My.xcodeproj")`

Start with the existing Xcodeproj::Workspace.new_from_xcworkspace(...).schemes and Xcodeproj::Project.schemes(...) entry points, then review the linked Stack Overflow question for how Xcode stores the active scheme. Done means defining and exposing Xcodeproj::Project.active_scheme("My.xcodeproj") with behavior that identifies the requested project's active scheme.

Written by the indexing model from the issue text.