Support schema property examples (extract)

[dsuket]

Description

Original request : #1165 (comment)
I extracted only the handling of property examples.

Additionally, I fixed an issue where a runtime error would occur if there was no schema definition for a mediaObject.

Motivation and Context

There was an issue with property examples not being displayed. I've made it so they are now visible.

How Has This Been Tested?

• Pass npm run build
• Pass npm run test
• I went through the demo API and tests and confirmed that the examples are being displayed properly.

Screenshots (if appropriate)

Before

[before] examples in request parameters schema

[before] examples of properties in requestBody schema

[before] examples of schema properties in response

After

[after] examples in request parameters schema

[after] examples of properties in requestBody schema

[after] examples of schema properties in response

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist

• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes if appropriate.
• All new and existing tests passed.