Add rosidl_auto_generate_inetrfaces function

[HansRobo]

Description

This pull-request adds rosidl_auto_generate_inetrfaces function to simplify boilerplate CMake in interface packages.

rosidl_auto_generate_inetrfaces function was originally planned as the ament_auto_generate_code function. However, when I implemented it in ament/ament_cmake#600, I was advised to move it to rosidl_cmake because ament_cmake's dependency on rosidl_cmake would create a circular dependency.

Using rosidl_auto_generate_inetrfaces simplifies CMake for interface packages as follows:

before

cmake_minimum_required(VERSION 3.12)
project(my_interfaces)

find_package(ament_cmake REQUIRED)
find_package(rosidl_default_generators REQUIRED)
find_package(std_msgs REQUIRED)

rosidl_generate_interfaces(${PROJECT_NAME}
  "msg/Test.msg"
  "msg/TestA.msg"
  "msg/TestB.msg"
  DEPENDENCIES std_msgs
  ADD_LINTER_TESTS
)

ament_export_dependencies(rosidl_default_runtime)

ament_package()

after

cmake_minimum_required(VERSION 3.12)
project(my_interfaces)

find_package(ament_cmake REQUIRED)
find_package(rosidl_default_generators REQUIRED)
find_package(std_msgs REQUIRED)

rosidl_auto_generate_interfaces(ADD_LINTER_TESTS)

ament_package()

Is this user-facing behavior change?

Did you use Generative AI?

I used Gemini 3.0 to review my code.

Additional Information

[fujitatomoya]

lgtm

[fujitatomoya]

@HansRobo is this still draft? it seems ready for review?

[HansRobo]

Yes, it's ready for review! I checked building with GitHub Actions.
https://github.com/HansRobo/ros2_sandbox/actions/runs/19841766914/job/56851537887