Add a way to pass extra parameters to ros_gz_bridge

[Amronos]

🎉 New feature

Closes #624

Summary

Added a new argument bridge_params to allow users to pass extra parameters to ros_gz_bridge when using the launch file. An example of these parameters would be qos_overrides
I have changed the node declarations to an opaque function so that I can get the value of bridge_params.
bridge_params is converted from string to dictionary and then passed to the parameters of the ros_gz_bridge node.
The way I have done all of this is complicated and so please do tell me if there is an easier way to do this.

Test it

To test this something like the following command can be used:
ros2 launch ros_gz_bridge ros_gz_bridge.launch.py bridge_name:=ros_gz_bridge config_file:=<path_to_your_YAML_file> bridge_params:="'qos_overrides./topic_name.publisher.durability': 'transient_local', 'qos_overrides./another_topic_name.publisher.durability': 'transient_local'"

Then to check if the qos overrides have applied:
ros2 topic info /topic_name --verbose
ros2 topic info /another_topic_name --verbose

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• Consider updating Python bindings (if the library has them)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

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[caguero]

There are some style errors. See https://github.com/gazebosim/ros_gz/actions/runs/11588839442/job/32263218643?pr=628

[azeey]

I haven't had time to dig into this, but it feels like a big code change for a fairly small feature. Is it the conversion from string to dictionary that requires the use of the opaque function? Another approach I would consider is moving more of the logic into the gz_server Action or even reverting the current architecture where the Action includes a launch file

ros_gz/ros_gz_bridge/ros_gz_bridge/actions/ros_gz_bridge.py

Lines 146 to 150 in 2658f27

	ros_gz_bridge_description = IncludeLaunchDescription(
	PythonLaunchDescriptionSource(
	[PathJoinSubstitution([FindPackageShare('ros_gz_bridge'),
	'launch',
	'ros_gz_bridge.launch.py'])]),

and instead have the ros_gz_bridge.launch.py file use the Action. It seems like we have more flexibility there.

[Amronos]

Is it the conversion from string to dictionary that requires the use of the opaque function?

Yes.

or even reverting the current architecture where the Action includes a launch file and instead have the ros_gz_bridge.launch.py file use the Action. It seems like we have more flexibility there.

That does sound like a good idea.