Add vehicle state last update time sensor

[natekspencer]

Potential breaking change

• The value/native_value, last_update and history data points stored in extra_state_attributes have been removed. A single Vehicle state last update time sensor, which stores the most recent state update timestamp, has been created in case there is a need/desire to check for "staleness" of data. This sensor is disabled by default, so you will need to enable it if you want to use it.