build(vendor): gate test interfaces to tests and doctests

[esteve]

This PR avoids including the test_msgs and example_interfaces packages when not building rclrs for testing.

[esteve]

This should fix #550 and maybe #616

[esteve]

Back to draft to figure out a better solution.

[maspe36]

Any chance someone can provide me with a minimal workspace where this occurs?

I did this

mkdir -p ~/test_ws/src && cd ~/test_ws/
ros2 pkg create --build-type ament_cargo foobin  --destination-directory src
colcon build
ldd build/foobin/debug/foobin | grep -i -E "test_msgs|example_interfaces|test_interface_files"

But there is no linkage to test_msgs or any of the other aforementioned packages. I also then tried to have rclrs in the workspace as a cargo path dependency for foobin

git clone git@github.com:ros2-rust/ros2_rust.git src/ros2_rust
rm -rf build/ log/ install/ .cargo/
sed -i 's|rclrs = "\*"|rclrs = { path = "../ros2_rust/rclrs" }|' src/foobin/Cargo.toml
colcon build
ldd build/foobin/debug/foobin | grep -i -E "test_msgs|example_interfaces|test_interface_files"

And finally I tried making sure rclrs was being patched in by colcon-ros-cargo in .cargo/config.toml

rm -rf build/ log/ install/ .cargo/

# Go back to the default "*" import from the package template
sed -i 's|rclrs = { path = "../ros2_rust/rclrs" }|rclrs = "*"|' src/foobin/Cargo.toml

sed -i '/<\/license>/a\  <depend>rclrs</depend>' src/foobin/package.xml
colcon build
ldd build/foobin/debug/foobin | grep -i -E "test_msgs|example_interfaces|test_interface_files"

But still, I am not seeing any linkage to these debug packages. Maybe I'm missing something but for now I'm not seeing the issue

[maspe36]

This means that these symbols now live under rclrs:: instead of ros_env::, that goes against the intent of the ros_env crate as the source for all ROS 2 message code