createOpenApiNuxtHandler should also export createOpenApiNitroHandler

[sannajammeh]

Nitro is the underlying engine behind Nuxt. Nitro can be used standalone as well. Consider having these exports for compatibility and to avoid developer confusion:

export const createOpenApiNuxtHandler = ...;
export const createOpenApiNitroHandler = createOpenApiNuxtHandler;

For developers working on a nitro only codebase, having Nuxt in the code is a little confusing when there is no Nuxt dependency.

Happy to make a pr! :)