Add `miniaturize`, `deminiaturize`, `performMiniaturize`, and `isMiniaturized` methods

[Adrian-Samoticha]

Add methods for the miniaturize*, deminiaturize, performMiniaturize, and isMiniaturized methods of the NSWindow.

None of those methods require any arguments (except for a sender, which may be nil), and are therefore very straightforward to implement, which is why I have marked this issue as a “good first issue”.

If this is your first time contributing to a macOS plugin, feel free to use the CONTRIBUTING.md file as guidance.

---

*The miniaturize method has already been implemented in #62.

[Adrian-Samoticha]

This issue was mistakenly mentioned in #46. It is currently not being actively worked on.

[Adrian-Samoticha]

This issue is now partially resolved by #62 (the PR only contains the miniaturize method, but not the deminiaturize, performMiniaturize, and isMiniaturized methods).

I will keep it open until the other methods are implemented as well.