BLE: Add APIs to get characteristic authorization callbacks.

connectivity/FEATURE_BLE/include/ble/gatt/GattCharacteristic.h

@@ -1579,6 +1579,17 @@ public:
         writeAuthorizationCallback.attach(object, member);
     }
 
+    /**
+     * Return the callback registered to handle client's write.
+     *
+     * @return the callback that handles client's write requests.
+     */
+    const FunctionPointerWithContext<GattWriteAuthCallbackParams *>&
+    getWriteAuthorizationCallback() const
+    {
+        return writeAuthorizationCallback;
+    }
+
     /**
      * Register the read requests event handler.
      *
@@ -1616,6 +1627,17 @@ public:
         readAuthorizationCallback.attach(object, member);
     }
 
+    /**
+     * Return the callback registered to handle client's read.
+     *
+     * @return the callback that handles client's read requests.
+     */
+    const FunctionPointerWithContext<GattReadAuthCallbackParams *>&
+    getReadAuthorizationCallback() const
+    {
+        return readAuthorizationCallback;
+    }
+
     /**
      * Invoke the write authorization callback.
      *