Add charging_state to VehicleSummary

[brianmay]

Fixes: #3078

This will publish the state to MQTT and allow sensing of the NoPower state.

[brianmay]

Notes:

1. Not tested yet. About to do that.
2. Wondering if I should add to @always_published which will publish nil values. But most likely reason for nil value is because vehicle.charge_state is nil, which means we don't know this value just yet, which means we shouldn't publish.

Actually thinking we shouldn't publish any vehicle.charge_state values if that value is nil, because it does mean we don't know what the value is. But fixing this beyond the scope of this simple pull request.

[brianmay]

As far as I can tell the CI test failures are unrelated.

[brianmay]

Preliminary testing seems to indicate it is working...

[JakobLichterfeld]

1. Not tested yet. About to do that.

Did you test it in the meantime?

[brianmay]

Yes, is tested and working. I see there is a conflict, will try to resolve that.

[brianmay]

I rebased this against the latest master.

[brianmay]

I think the test errors are not connected to this PR.

[JakobLichterfeld]

lgtm, failed CI is handled in #3428