[pixometer] Follow up enhancements after initial binding implementation

[Confectrician]

This is meant to be a storage for my "to-do's" that are based on the PR discussion from #4162.

Next steps should be:

• Introduce API related content in a special class ([pixometer] Pixometer Binding initial contribution #4162 (comment))
• Move all API calls into the bridge implementation as a central point of the connection ([pixometer] Pixometer Binding initial contribution #4162 (comment))
• Let things request api contents from the bridge
• Use api responses for a more granular error handling ([pixometer] Pixometer Binding initial contribution #4162 (comment))

[hmerk]

@Confectrician Are you still working on this or should we close this issue ?

[Confectrician]

I am not sure if I will come back to pixometer at all. So we can close this one.

I will find it in case it will be useful again. :)