feat: 支持获取 maximumWrtieLength (#14)

bluetooth_low_energy_platform_interface/lib/src/central_controller.dart

@@ -73,6 +73,12 @@ abstract class CentralController extends PlatformInterface {
   /// Disconnects form the peripheral.
   Future<void> disconnect(Peripheral peripheral);
 
+  /// Gets the max length in bytes for a single write type of the peripheral.
+  Future<int> getMaximumWriteLength(
+    Peripheral peripheral, {
+    required GattCharacteristicWriteType type,
+  });
+
   /// Discovers GATT of the peripheral.
   Future<void> discoverGATT(Peripheral peripheral);