add specific properties support for alexa smart properties

[nachawat]

Hello,

To ensure request payload sent to Alexa Skills while in the context of Alexa Smart Properties (e.g Alexa for Hospitality or Alexa for Residential) is fully deserialized, a few additional properties must be added.

From the official Request and Response JSON Reference Alexa documentation, you can find the following properties to add into deserialization:

• persistentEndpointId is a persistent identifier for the endpoint from which the skill request is issued. This property shall be added into the existing Device object.

• unitId is a string representing a unique identifier for the unit in the context of a request. This property shall be added into a new object named Unit attached to the existing System object.

• persistentUnitId is a string representing a unique identifier for the unit in the context of a request. This property shall be added into a new object named Unit attached to the existing System object.

The objective of this PR is to add support for those 3 properties into the request payload sent to skills.

Thank you Benoit

[timheuer]

Thanks for the contribution @nachawat I'm taking a look now -- one test is failing.

@all-contributors please add @nachawat for code

[allcontributors[bot]]

@timheuer

I've put up a pull request to add @nachawat! :tada: