Add a settings key and settings UI to the GUI

[andrewtavis]

Terms

• I have searched open and closed feature requests
• I agree to follow Scribe-Desktop's Code of Conduct

Description

This issue would add the settings icon when the user has pressed the settings button as shown in the Scribe-Desktop designs.

The settings would for now just have the interface theme as an option instead of the command keys (translate, conjugate and plural).

Contribution

Happy to support with this and review a PR! 😊