cm: communication: add message handler interface

This patch adds an interface that is capable of handling messages
received from by the communication module.

Signed-off-by: Mykhailo Lohvynenko <mykhailo_lohvynenko@epam.com>

Author: mlohvynenko

include/aos/cm/communication/communication.hpp

@@ -16,6 +16,25 @@ namespace aos::cm::communication {
  *  @{
  */
 
+/**
+ * Message handler interface to handle received message.
+ */
+class MessageHandlerItf {
+public:
+    /**
+     * Handles received message.
+     *
+     * @param message received message.
+     * @return Error.
+     */
+    virtual Error HandleMessage(const cloudprotocol::MessageVariant& message) = 0;
+
+    /**
+     * Destructor.
+     */
+    virtual ~MessageHandlerItf() = default;
+};
+
 /**
  * Connection events subscriber interface.
  */