Add support for service responses

[frenck]

Description

Add support to the framework for handling services that respond with data.

I did notice some weirdness, like: It seems like Home Assistant doesn't support this concept for admin services (likely a miss, but I don't see the use case at this point either).

Motivation and Context

So we can add some awesome services.

How has this been tested?

I didn't.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.