OAS 3.2.0 examples changes

[mattpolzin]

Examples as either structured or serialized values

• The Example Object (used in examples fields) gets two new fields: dataValue and serializedValue.
• dataValue describes the example in structured format.
• serializedValue shows how the example will be formatted when it is sent/received by the API.
• The existing externalValue field can still be used to give a reference to an example, but this is now clearly documented as being a serialized value.