fix: support custom attributes as functions (do not execute them)

[sandrina-p]

This one is hard to explain with words alone. Here's a Loom (public) explaining the real problem, the path to the solution.

• Codesandbox mentioned in Loom
• Codesandbox fixed (using latest dev release version

Linear ticket

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TLDR:

Before a JSON Schema like this would throw an error, but now it works well:

This schema includes a conditional field field_b with a custom attribute x-jsf-presentation.MyComponent which is a function. Before createHeadlessForm() would execute it even though it's not necessary

const { fields, handleValidation } = createHeadlessForm({
  properties: {
    field_a: {
      title: 'A field',
      'x-jsf-presentation': {
        inputType: 'text',
      },
    },
    field_b: {
      title: 'Field B',
      'x-jsf-presentation': {
        inputType: 'text',
        MyComponent: function MyComponent(props) {
          // 🐛 ✅ This now works! Before it would explode trying to run this (when it shouldn't).
          const { label, description } = props;
          return `A fake React component with ${label} and ${description}`;
        },
      },
    },
  },
  allOf: [
    {
      if: {
        properties: {
          field_a: { const: 'yes' },
        },
        required: ['field_a'],
      },
      then: {
        required: ['field_b'],
      },
    },
  ],
});

[brennj]

Based on the loom and testing this internally, happy for this to go in!