BYD Atto 3: Add way to use SOC% sent by battery

[dalathegreat]

What

This PR adds a configurable option to use SOC% sent by battery

Why

When Atto 3 packs are crashed hard, they lock themselves and stop updating SOC%. Our previous implementation instead estimates SOC% via battery voltage. This solution is bad, since putting load on the battery will make the reading swing, this making it impossible to use the whole battery.

How

We add a configurable option to the BYD-ATTO-3-BATTERY.h file. If you are certain that your battery is not crashed hard, you can remove the line USE_ESTIMATED_SOC, and the code will then instead use the periodically transmitted SOC value. :information_source: If your battery IS locked and you remove this line, SOC% will stay stuck at the value it had when the battery was crashed and airbags popped.