Expose `InertiaAppProps` type from the index

[apademide]

Because the <App /> component receives InertiaAppProps as its props, using said type elsewhere is sometimes required. Currently, it's accessible by digging to "inertia-adapter-solid/dist/types/App", which would work but isn't too pretty.

This one liner PR (despite having 7 commits, git rebases ftw) simply exposes the type from the index file, so import { type InertiaAppProps } from "inertia-adapter-solid" works. This also makes it more convenient for tsconfig using stricter module resolution modes ("moduleResolution": "bundler" in mind here), where "inertia-adapter-solid/dist/types/App" is not recognised at all.