feat: support zod native string date-time

[vargasd]

Currently the native z.string().datetime() is not supported. While ZodDateString handles this, it means for my project that nestjs-zod has to be used in a lower-level package, rather than just in the api/nestjs package where it does the appropriate work on top of the base types.

[mbsanchez01]

I vote for z.string().datetime() and z.string().date() to be supported too, I'm using openapi-zod-client to generate a client for one specific API, and it generates schemas using z.string().datetime() and z.string().date(), so, it will be great if you can add support for those.