When a component is in runes mode and not using slots or events, adjust the output to only create the function type that mimics the underlying real shape of components in Svelte 5. This is a breaking change because previously the type was enhanced such that it also had the legacy class shape. As a result, users now may need to switch to `typeof Component` when using the component inside types.

…s, we need to always create both a legacy class component and function component type.

 - Constraints: Need to support Svelte 4 class component types, therefore we need to use __sveltets_2_ensureComponent to transform function components to classes
- Limitations: TypeScript is not able to preserve generics during said transformation (i.e. there's no way to express keeping the generic etc)
TODO Svelte 6/7: Switch this around and not use new Component in svelte2tsx anymore, which means we can remove the legacy class component. We need something like _ensureFnComponent then.