Add gpui-kit cli similar to shadcn cli to allow to easily add and share components

[prabirshrestha]

Any plans to add something similar to https://ui.shadcn.com/docs/cli and https://ui.shadcn.com/docs/directory where one can easily pull in components. I like how in shadcn the component is part of the source code so it is easy to pull it in and modify if needed.