Allow user handling of `format` strings in OpenAPI

[ntjess]

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Description

From OpenAPI docs:

As defined by the JSON Schema Validation vocabulary, data types can have an optional modifier property: format. OAS defines additional formats to provide fine detail for primitive data type

The referenced JSON schema includes this:

Structural validation alone may be insufficient to allow an application to correctly utilize certain values. The "format" annotation keyword is defined to allow schema authors to convey semantic information for a fixed subset of values which are accurately described by authoritative resources, be they RFCs or other external specifications.

TLDR: It's a way for generic types like string to be given more semantic meaning (by defining a format: uuid as an example).

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It would be great if openapi-ts allowed intercepting of common formats (as defined in the JSON spec referenced above), allowing clients to handle them as branded types / custom classes/validators / etc.

Here's one example that would be useful for me:

OpenAPI spec snippet:

 "components": {
    "schemas": {
      "MyObject": {
        "properties": {
          "Id": {
            "type": "string",
            "format": "uuid4",
            // ^ Relevant portion here
            "title": "Id"
          },
// ... definition continues

I'm not sure what a middleware spec inside hey-api would look like, but hopefully this issue gets the ball rolling on client-defined conversion of known subtypes of primitives like string/number.

Thanks for considering!