Add diagnostic bit support to Gateway Modbus

- Introduced new enum value `kShortDiagnosticBit` to `GatewayModbusGeneratedKind`.
- Enhanced `GatewayModbusPoint` and `GatewayModbusPointBinding` structures to include diagnostic snapshot, boolean key, and device type.
- Added new diagnostic bit specifications and updated the corresponding arrays for generated discrete inputs and holding registers.
- Implemented `addGeneratedDiagnosticPoint` function to handle the creation of diagnostic points.
- Updated `rebuildMap` method to include generated diagnostic points during the map rebuilding process.

Co-authored-by: Copilot <copilot@github.com>

components/gateway_modbus/include/gateway_modbus.hpp

@@ -79,6 +79,7 @@ enum class GatewayModbusGeneratedKind : uint8_t {
   kShortActualLevel,
   kShortSceneId,
   kShortRawStatus,
+  kShortDiagnosticBit,
 };
 
 struct GatewayModbusPoint {
@@ -93,6 +94,9 @@ struct GatewayModbusPoint {
   std::string model_id;
   BridgeOperation operation{BridgeOperation::unknown};
   std::optional<int> bit_index;
+  std::string diagnostic_snapshot;
+  std::string diagnostic_bool;
+  int diagnostic_device_type{-1};
 };
 
 struct GatewayModbusPointBinding {
@@ -105,6 +109,10 @@ struct GatewayModbusPointBinding {
   GatewayModbusGeneratedKind generated_kind{GatewayModbusGeneratedKind::kNone};
   int short_address{-1};
   GatewayModbusAccess access{GatewayModbusAccess::kReadWrite};
+  std::optional<int> bit_index;
+  std::string diagnostic_snapshot;
+  std::string diagnostic_bool;
+  int diagnostic_device_type{-1};
 };
 
 std::optional<GatewayModbusConfig> GatewayModbusConfigFromValue(const DaliValue* value);