Add ability for param_listener to load values from yaml dictionary

generate_parameter_library_py/generate_parameter_library_py/jinja_templates/python/parameter_library_header

@@ -10,11 +10,34 @@ 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 -%}
 import {{user_validation_file}} as custom_validators
-{% endif %}
+{% endif -%}
+
+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
+
 
 class {{namespace}}:
 {%- filter indent(width=4) %}
@@ -53,6 +76,10 @@ stamp_ = Time()
         def is_old(self, other_param):
             return self.params_.stamp_ != other_param.stamp_
 
+        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