fix: Add case to handle x-examples value of body param.

[userwiths]

Allow populating body with default values described in x-examples

Description

Changes done here are to allow the use of x-examples inside a (body) parameter in order to populate it with default values.

Motivation and Context

Fixes: #3233

How Has This Been Tested?

Manually.
Attempts were made to write unit tests, but I could not get the code (test\unit\components\parameter-row.jsx) to render deep enough in order to get the text of the code element.

The change in the Api declaration I used to test looks like this (can be compared with screenshots bellow).
This is the parameters declaration on the POST /pet method I used to test.

"parameters":[
    {
        "in":"body",
        "name":"body",
        "description":"Pet object that needs to be added to the store",
        "required":true,
        "schema":{
            "$ref":"#/definitions/Pet"
        },
        "x-examples":{
            "default":{
            "id": 101,
            "name":"brand-new-doggie",
            "photoUrls":[
                "http://example.com/doggie.jpg"
            ],
            "tags":[
                {
                    "id": 101,
                    "name":"tag101"
                }
            ],
            "status":"custom-available"
            }
        }
    }
],

Screenshots (if appropriate):

The above changed declaration resulted in the following:

Checklist

My PR contains...

• No code changes (src/ is unmodified: changes to documentation, CI, metadata, etc.)
• Dependency changes (any modification to dependencies in package.json)
• Bug fixes (non-breaking change which fixes an issue)
• Improvements (misc. changes to existing features)
• Features (non-breaking change which adds functionality)

My changes...

• are breaking changes to a public API (config options, System API, major UI change, etc).
• are breaking changes to a private API (Redux, component props, utility functions, etc.).
• are breaking changes to a developer API (npm script behavior changes, new dev system dependencies, etc).
• are not breaking changes.

Documentation

• My changes do not require a change to the project documentation.
• My changes require a change to the project documentation.
• If yes to above: I have updated the documentation accordingly.

Automated tests

Attempts to add unit tests were unsuccessful because I could not get the whole DOM subtree to render.
Last thing it gave me was a div with with objects passed as attributes to it. If you have an idea how this can be tested or know of tests I could use as example just point it out to me and Im see if I can introduce tests.

• My changes can not or do not need to be tested.
• My changes can and should be tested by unit and/or integration tests.
• If yes to above: I have added tests to cover my changes.
• If yes to above: I have taken care to cover edge cases in my tests.
• All new and existing tests passed.