Mark form parameters as required when body is required

[skrysmanski]

This pull request fixes the problem that when a form request body is marked as "required", then all form parameters should also be marked as "required".

For example, take this (shortened) input spec:

paths:
  /test_required:
    post:
      summary: Operation with form body that is required
      requestBody:
        required: true
        content:
          application/x-www-form-urlencoded:
            schema:
              $ref: '#/components/schemas/Category'

components:
  schemas:
    Category:
      type: object
      properties:
        id:
          type: integer
          format: int64
        name:
          type: string

It results in 2 form parameters (id and name). Without this fix both parameters would be marked as "optional", even though the request body is marked as "required".

[HugoMario]

awesome, thanks !!!