Fix field type validation for actions

[vpfkfl753]

Description

Fixes #829.

validate_field_types() raises AttributeError for parsed actions because ActionSpecification has no goal_service or result_service. Read the goal, result and feedback fields directly, and remove the unused service annotations.

Is this user-facing behavior change?

Action validation now accepts valid fields and raises UnknownMessageType for unknown message types in any of the three sections.

Did you use Generative AI?

Yes, OpenAI Codex (GPT-6), for the code change and tests.

Additional Information

Added five regression cases for empty actions, primitive fields and unknown message types in each section. All five fail before the fix. The adapter's 46 Python tests pass in a ROS 2 Rolling container.

colcon build and colcon test --packages-select rosidl_adapter also pass, including mypy and the package's lint checks.

[fujitatomoya]

lgtm with green CI.

[ahcorde]

Pulls: #993
Gist: https://gist.githubusercontent.com/ahcorde/532874aec5328a718400d107ff3c0169/raw/8f04a18c03d43996c538a550951d5106262719a3/ros2.repos
BUILD args: --packages-above-and-dependencies rosidl_adapter
TEST args: --packages-above rosidl_adapter
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/20411

• Linux
• Linux-aarch64
• Linux-rhel
• Windows

[vpfkfl753]

Linux, Linux-aarch64 and RHEL passed. The Windows build stopped before tests while compiling rviz_default_plugins:

error C1083: Cannot open include file: 'rclcpp/macros.hpp': No such file or directory

rosidl_adapter built successfully. The missing header is also present in the rclcpp revision used by the job, so this looks unrelated to the changes here. Could the Windows job be rerun?