Dialog API types are not present on `ExtensionManager` for custom nodes

The `dialog` object on `app.extensionManager` has a type of `any`

This **does not** affect the actual functionality of the Dialog API, it is only the type hints that do not work

The Dialog API type is defined as `ReturnType`.

During the build step for the frontend type library, several errors are emitted related to this type definition.

**Potential Solution**: Define the public api of useDialogService and export that instead

┆Issue is synchronized with this [Notion page](https://www.notion.so/Issue-6204-Dialog-API-types-are-not-present-on-ExtensionManager-for-custom-nodes-2946d73d36508161a938e7daa42f3bb4) by [Unito](https://www.unito.io)