Agent: Add from_dict method to AgentConfiguration

Creating AgentConfiguration object from dictionary makes sense because it doesn't couple the configuration to any specific serialization methods. Also, the json sent from the island doesn't match the config structure because it stores config in a dict under "config" key.

monkey/common/configuration/agent_configuration.py

@@ -24,6 +24,10 @@ class AgentConfiguration:
     payloads: List[PluginConfiguration]
     propagation: PropagationConfiguration
 
+    @staticmethod
+    def from_dict(_dict: dict):
+        return AgentConfigurationSchema().load(_dict)
+
 
 class AgentConfigurationSchema(Schema):
     keep_tunnel_open_time = fields.Float()