ProjectEV(Atess) chargers return empty responses to config messages b…

[archerjm]

…ut are smart enabled chargers. Support these by making the default type core plus smart in the case fo an empty message and protect the set_charging_rate calls against the empty responses that these chargers generate.

[drc38]

Defaulting in the code to "Core with Smart Charging" will cause issues in the integration for those chargers that don't support the Smart Charging profile. I suggest adding this to the Configuration Flow as a tickbox option eg "Add manual support for Smart Charging". This approach would also resolve the example in #474

Defaulting to a stack level of 0 when a response is blank looks fine to me.

[drc38]

@archerjm try the latest release and feel free to do another PR if needed