Implement AC charger feedback via CAN

[uhi22]

Clara shall receive via CAN the following information from AC charger:

• locking and unlocking the connector
• switch the 1k3 on and off
• switch the LEDs (e.g. green flashing = init, blue=charging, blue/green=finished)

Discussion: https://openinverter.org/forum/viewtopic.php?p=66713#p66713

[uhi22]

Progress: Ready for AC charging:

• Clara provides the current limitation of the cable in cableCurrentLimit.
• Clara provides the current limit of the AC charging station in evseCurrentLimit.
• Clara receives the control for LEDs and 1k3 resistor in AcObcState. Clara only uses this, if a valid PWM was detected.
  Still open:
• triggering of the connector locking and unlocking. For this, especially the unlocking, the strategy needs to be defined.
• switching back to DC mode. At the moment, a power-on of clara is needed to go back from AC mode to DC mode. This can be improved.

[uhi22]

implemented now: switching back to DC mode if we detect 5% PWM for half a second.

Still open: connector locking and unlocking for AC case. Strategy needs to be defined.