Pytes battery: Add support for native CAN protocol

The recently added PytesCanReceiver.cpp implements the Victron CAN
protocol.

This change additionally adds support for the native Pytes CAN
protocol messages.

Features only supported in Pytes protocol:
- High-resolution state of charge / full and remaining mAh
- Charge cycle counter
- Balancing state

Features only supported in Victron protocol:
- FW version
- Serial number

Note that the only known way to select the native Pytes protocol is
via the serial console (Cisco-compatible cables work):

```
login config
setprt PYTES
logout
```

to return to Victron protocol use:
```
login config
setprt VICTRON
logout
```

The protocol switch will take effect immediately.

Tested on Pytes E-Box 4850

See #1188

include/BatteryStats.h

@@ -134,6 +134,7 @@ class PytesBatteryStats : public BatteryStats {
     public:
         void getLiveViewData(JsonVariant& root) const final;
         void mqttPublish() const final;
+        bool getImmediateChargingRequest() const { return _chargeImmediately; } ;
         float getChargeCurrentLimitation() const { return _chargeCurrentLimit; } ;
 
     private:
@@ -154,6 +155,8 @@ class PytesBatteryStats : public BatteryStats {
         float _dischargeCurrentLimit;
 
         uint16_t _stateOfHealth;
+        int _chargeCycles = -1;
+        int _balance = -1;
 
         float _temperature;
 
@@ -173,8 +176,9 @@ class PytesBatteryStats : public BatteryStats {
         uint8_t _moduleCountBlockingCharge;
         uint8_t _moduleCountBlockingDischarge;
 
-        uint16_t _totalCapacity;
-        uint16_t _availableCapacity;
+        float _totalCapacity;
+        float _availableCapacity;
+        uint8_t _capacityPrecision = 0; // decimal places
 
         float _chargedEnergy = -1;
         float _dischargedEnergy = -1;
@@ -200,6 +204,8 @@ class PytesBatteryStats : public BatteryStats {
         bool _warningHighTemperatureCharge;
         bool _warningInternalFailure;
         bool _warningCellImbalance;
+
+        bool _chargeImmediately;
 };
 
 class JkBmsBatteryStats : public BatteryStats {

src/BatteryStats.cpp

@@ -129,10 +129,13 @@ void PytesBatteryStats::getLiveViewData(JsonVariant& root) const
     addLiveViewValue(root, "dischargeVoltageLimitation", _dischargeVoltageLimit, "V", 1);
     addLiveViewValue(root, "dischargeCurrentLimitation", _dischargeCurrentLimit, "A", 1);
     addLiveViewValue(root, "stateOfHealth", _stateOfHealth, "%", 0);
+    if (_chargeCycles != -1) {
+        addLiveViewValue(root, "chargeCycles", _chargeCycles, "", 0);
+    }
     addLiveViewValue(root, "temperature", _temperature, "°C", 1);
 
-    addLiveViewValue(root, "capacity", _totalCapacity, "Ah", 0);
-    addLiveViewValue(root, "availableCapacity", _availableCapacity, "Ah", 0);
+    addLiveViewValue(root, "capacity", _totalCapacity, "Ah", _capacityPrecision);
+    addLiveViewValue(root, "availableCapacity", _availableCapacity, "Ah", _capacityPrecision);
 
     if (_chargedEnergy != -1) {
         addLiveViewValue(root, "chargedEnergy", _chargedEnergy, "kWh", 1);
@@ -142,6 +145,11 @@ void PytesBatteryStats::getLiveViewData(JsonVariant& root) const
         addLiveViewValue(root, "dischargedEnergy", _dischargedEnergy, "kWh", 1);
     }
 
+    if (_balance != -1) {
+        addLiveViewTextValue(root, "balancingActive", (_balance?"yes":"no"));
+    }
+    addLiveViewTextValue(root, "chargeImmediately", (_chargeImmediately?"yes":"no"));
+
     addLiveViewInSection(root, "cells", "cellMinVoltage", static_cast<float>(_cellMinMilliVolt)/1000, "V", 3);
     addLiveViewInSection(root, "cells", "cellMaxVoltage", static_cast<float>(_cellMaxMilliVolt)/1000, "V", 3);
     addLiveViewInSection(root, "cells", "cellDiffVoltage", (_cellMaxMilliVolt - _cellMinMilliVolt), "mV", 0);
@@ -347,6 +355,12 @@ void PytesBatteryStats::mqttPublish() const
     MqttSettings.publish("battery/settings/dischargeVoltageLimitation", String(_dischargeVoltageLimit));
 
     MqttSettings.publish("battery/stateOfHealth", String(_stateOfHealth));
+    if (_chargeCycles != -1) {
+        MqttSettings.publish("battery/chargeCycles", String(_chargeCycles));
+    }
+    if (_balance != -1) {
+        MqttSettings.publish("battery/balancingActive", String(_balance ? 1 : 0));
+    }
     MqttSettings.publish("battery/temperature", String(_temperature));
 
     if (_chargedEnergy != -1) {
@@ -396,6 +410,7 @@ void PytesBatteryStats::mqttPublish() const
     MqttSettings.publish("battery/warning/highTemperatureCharge", String(_warningHighTemperatureCharge));
     MqttSettings.publish("battery/warning/bmsInternal", String(_warningInternalFailure));
     MqttSettings.publish("battery/warning/cellImbalance", String(_warningCellImbalance));
+    MqttSettings.publish("battery/charging/chargeImmediately", String(_chargeImmediately));
 }
 
 void JkBmsBatteryStats::mqttPublish() const