fix: compound types

[markandrus]

I noticed a bug with allOf on object types. The intersection types were not constructed correctly. I took the same testing approach as #10.

Given the following schema

openapi: 3.0.3
info:
  description: Title
  version: 1.0.0
servers:
  - url: https

components:
  schemas:
    A:
      type: object
      properties:
        a:
          type: string
    AB:
      type: object
      properties:
        b:
          type: string
      allOf:
        - $ref: '#/components/schemas/A'

Before this change

const _components = {
  schemas: {
    A: CloneType(ComponentsSchemasA),
    AB: T.Intersect([CloneType(ComponentsSchemasA)], {
      properties: { b: { type: 'string' } }
    })
  }
}

After this change

const _components = {
  schemas: {
    A: CloneType(ComponentsSchemasA),
    AB: T.Intersect([
      CloneType(ComponentsSchemasA),
      T.Object({
        b: T.Optional(T.String())
      })
    ])
  }
}

[tinchoz49]

This looks great! thank you @markandrus