Added support for Energy Sites

[giachello]

I added support for Energy Sites (Solar Panels). This has been working for my installation for a week now and feeds into my Energy panel on Home Assistant. I know you wanted to restructure the entire API in a separate thread on this topic, but I'm not going to do that work (don't have the time).

This goes together with a pull request on the Tesla custom component.

[alandtse]

Thanks. Please address the version/changelog reversion and lint errors and we'll get this merged in this weekend.

[giachello]

Ok, I think I took care of all the comments you left. Let me know!

[shred86]

Hey @giachello, I'm helping with the rewrite and had a question on some changes in this pull request (thanks for adding this by the way!). I was wondering what the thought was behind mapping the site_id to energysite_id?

        self.__id_energysiteid_map = {}
        self.__energysiteid_id_map = {}

It looks like all the power data is stored in self.__power which is organized by energysite_id, so even someone that has two energy sites, I can still just pull the data I need using energysite_id. I'm sure there's a good reason, I'm just a novice programmer so I'm trying to understand before I make any major changes. Thanks!

[giachello]

Actually, I think I've just done that for completeness, to conform with the way that the Car entities were written at the time. Not sure if there is a real need to do this.

[alandtse]

CarIDs are subject to change so it's possible they may change within a session so we had to translate it. If the energy sites cannot change, then you wouldn't need it.

[shred86]

Ahh okay, that makes sense. I'm not 100% certain but I have not noticed the energy_site_id change. I haven't really looked closely at just the "id", but I'll keep an eye on it. Thanks!