Convert Systemguard + Available Power to individual signals

[CVLenerginet]

Custom signals 1, 2 and 3 is now generally used in the testcases sheet to reflect percentage setpoint of systemguard, available power and activation of system guard. These should instead be made into specific signals of the MTB, notably reflecting:

• Systemguard activation
• Systemguard setpoint (not percentage but rather the step/level)
• Available Power (Ideally 1, 2 & 3 to cover most cases)