ActionSpecification in `rosidl_adapter.parser` missing attributes.

[InvincibleRMC]

Bug report

While doing #828 I noticed the following.

Required Info:

In this definition there is no goal_service or result_service.

rosidl/rosidl_adapter/rosidl_adapter/parser.py

Lines 870 to 881 in da9b4a4

	class ActionSpecification:
	def __init__(self, pkg_name, action_name, goal, result, feedback):
	self.pkg_name = pkg_name
	self.action_name = action_name
	assert isinstance(goal, MessageSpecification)
	self.goal = goal
	assert isinstance(result, MessageSpecification)
	self.result = result
	assert isinstance(feedback, MessageSpecification)
	self.feedback = feedback

But they are used here

rosidl/rosidl_adapter/rosidl_adapter/parser.py

Lines 801 to 806 in da9b4a4

	elif isinstance(spec, ActionSpecification):
	spec_type = 'Action'
	fields = []
	for service in [spec.goal_service, spec.result_service]:
	fields += service.request.fields
	fields += service.response.fields