Support union types for zod generator

[alisabzevari]

Fixes #236
Fixes #181

This PR adds support for union types for generating zod schemas when withObjectType is enabled.

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@alisabzevari Thanks!
Could you add code also yup and myzod?

[alisabzevari]

Sure, will do.

[alisabzevari]

I have added support for myzod but apparently yup does not support unions.

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@alisabzevari I believe you can use mixed and oneof for yup

[alisabzevari]

I believe you can use mixed and oneof for yup

I tried that but the generated schema cannot properly validate the object.

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@alisabzevari Could you add this code for yup in initialEmit: prop ?

function union<T>(...schemas: ReadonlyArray<yup.SchemaOf<T>>): yup.BaseSchema<T> {
  return yup.mixed().test({
    test: (value) => schemas.some((schema) => schema.isValidSync(value))
  })
}

And fix yup generator to generate code like below

function ShapeSchema(): yup.BaseSchema<Shape> {
  return union<Shape>(SquareSchema(), CircleSchema())
}

[alisabzevari]

I have added the code you mentioned. Please have a look.

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@alisabzevari Could you please fix the test?

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Thanks!