Add current offset for POWER_MONITOR sensor (#18600)

Marlin/Configuration_adv.h

 //#define POWER_MONITOR_VOLTAGE   // Monitor the system voltage
 #if EITHER(POWER_MONITOR_CURRENT, POWER_MONITOR_VOLTAGE)
   #define POWER_MONITOR_VOLTS_PER_AMP   0.05000   // Input voltage to the MCU analog pin per amp  - DO NOT apply more than ADC_VREF!
+  #define POWER_MONITOR_CURRENT_OFFSET -1         // Offset value for current sensors with linear function output  
   #define POWER_MONITOR_VOLTS_PER_VOLT  0.11786   // Input voltage to the MCU analog pin per volt - DO NOT apply more than ADC_VREF!
   #define POWER_MONITOR_FIXED_VOLTAGE   13.6      // Voltage for a current sensor with no voltage sensor (for power display)
 #endif

Marlin/src/feature/power_monitor.h

     filter_buf = filter_buf - (filter_buf >> K_VALUE) + (uint32_t(sample) << K_SCALE);
   }
   void capture() {
-    value = filter_buf * (SCALE * (1.0f / (1UL << (PM_K_VALUE + PM_K_SCALE))));
+    value = filter_buf * (SCALE * (1.0f / (1UL << (PM_K_VALUE + PM_K_SCALE)))) + (POWER_MONITOR_CURRENT_OFFSET);
   }
   void reset(uint16_t reset_value = 0) {
     filter_buf = uint32_t(reset_value) << (K_VALUE + K_SCALE);