Support for deepObject nested object and array of primitives query parameters

[danicc097]

Due to the recent changes of getkin/kin-openapi#911, I was wondering if you'd be willing to support the same functionality, i.e. nested objects with arrays of primitives (for deepObject explode: true params). Arrays of objects are purposedly not supported

runtime currently parses nested objects with a primitive properly, e.g. ?nested[obj][nestedObj]=string

        - in: query
          name: nested
          style: deepObject
          explode: true
          allowReserved: true
          schema:
            type: object
            properties:
              obj:
                type: object
                properties:
                  nestedObj:
                    type: string 

but it fails on a nested array (either ignoring an element when given one, or erroring out: https://github.com/oapi-codegen/runtime/blob/main/deepobject.go#L137).
It also errors out when the nested array field has a sibling field:
Invalid format for parameter nested: error assigning value to destination: error assigning field [obj]: field [authors] is not present in destination object

// - in: query
//   name: nested
//   style: deepObject
//   explode: true
//   allowReserved: true
//   schema:
//     type: object
//     properties:
//       obj:
//         type: object
//         properties:
//           nestedObj:
//             type: string
//           authors:
//             type: array
//             items:
//               type: string
{
  "obj": {
    "nestedObj": "string",
    "authors": [
      "string"
    ]
  }
}

As far as I've seen, it would also need changes to marshalDeepObject, since it adds array subscripts that would interfere with nested object keys, e.g. it marshals p[onas][Names][0]=Bill&p[onas][Names][1]=Frank instead of just p[onas][Names]=Bill&p[onas][Names]=Frank.

Probably missing other stuff. Please let me know if you have some thoughts on this. Some examples:

• https://github.com/getkin/kin-openapi/blob/05ccac23d287d8b25daf7a897e8868291ec53e81/openapi3filter/req_resp_decoder_test.go#L782
• https://github.com/getkin/kin-openapi/blob/05ccac23d287d8b25daf7a897e8868291ec53e81/openapi3filter/req_resp_decoder_test.go#L812