Matt Glaman: Improving the Drupal theme starterkit and theme generation experience

Wanting to follow up on our work at MidCamp 2023 with the Development Settings form, Mike Herchel wanted to jam on another issue to improve the life of frontend developers. Drupal provides a way to generate themes from starterkit themes. Drupal core provides the Starterkit theme, and contributed themes can also mark themselves as a starterkit theme. All a theme has to do is have starterkit: true in their info.yml file. And that's it! Optionally, a specifically named PHP file can be provided in the theme for specific processing to finish generating the new theme. Unfortunately, the experience of creating starterkit themes currently involves writing a lot of PHP code to make the required file alterations.