Add ability for param_listener to load values from yaml dictionary (#211)

Author: MarqRazz

generate_parameter_library_py/generate_parameter_library_py/jinja_templates/python/parameter_library_header

@@ -10,6 +10,7 @@ from rclpy.exceptions import InvalidParameterValueException
 from rclpy.time import Time
 import copy
 import rclpy
+import rclpy.parameter
 from generate_parameter_library_py.python_validators import ParameterValidators
 
 {% if user_validation_file|length -%}
@@ -53,6 +54,32 @@ stamp_ = Time()
         def is_old(self, other_param):
             return self.params_.stamp_ != other_param.stamp_
 
+        @staticmethod
+        def unpack_parameter_dict(namespace: str, parameter_dict: dict):
+            """
+            Flatten a parameter dictionary recursively.
+
+            :param namespace: The namespace to prepend to the parameter names.
+            :param parameter_dict: A dictionary of parameters keyed by the parameter names
+            :return: A list of rclpy Parameter objects
+            """
+            parameters = []
+            for param_name, param_value in parameter_dict.items():
+                full_param_name = namespace + param_name
+                # Unroll nested parameters
+                if isinstance(param_value, dict):
+                    nested_params = unpack_parameter_dict(
+                            namespace=full_param_name + rclpy.parameter.PARAMETER_SEPARATOR_STRING,
+                            parameter_dict=param_value)
+                    parameters.extend(nested_params)
+                else:
+                    parameters.append(rclpy.parameter.Parameter(full_param_name, value=param_value))
+            return parameters
+
+        def set_params_from_dict(self, param_dict):
+            params_to_set = unpack_parameter_dict('', param_dict)
+            self.update(params_to_set)
+
         def refresh_dynamic_parameters(self):
             updated_params = self.get_params()
             # TODO remove any destroyed dynamic parameters