Hoist Astro's type generation for type saftey in authoring enviroments

[BryceRussell]

When developing a theme, types are generated inside a playground. This makes it hard to properly link types while developing a theme. To improve this, types could also be generated inside the theme package to prevent issues with hoisting or circular type references.

Things to consider:

• Types are generated using the AIK utility addDts. This utility only generates types inside a user project, this issue would require a custom utility (or an upstream addition to AIK) for type generation inside a package
• Where are these types generated inside a package? virtual.d.ts?

[BryceRussell]

I am going to take over this issue and rename it, I worded it poorly and didn't explain exactly why I created it. Generating types inside the theme's package may have some advantages, but I don't know of any right now.

The real issue here is that theme authors need Content Collections types while developing inside a package.

This is a bit complicated because we need to generate the Content Collection types inside a playground and hoist them somehow so that authors have type safety when creating theme packages.

TLDR: Typically, types flow downwards from packages to users. We need to pass types upwards from a user to a package.