Export Vue's InertiaFormProps

[Spice-King]

This is needed to solve type issues for a laravel/precognition PR that I'm creating. I blame Typescript for this, as for some reason, TS needs the type exported to be used as part of another packages exports, even indirectly, otherwise you can get TS error 4023. Precognition only does Vue 3, but also added it to Vue 2 for constancy reasons.