Added ROS parameter instead of gflag to ros_gz_sim::create

[yaswanth1701]

🎉 New feature

Closes #459

Summary

Replaced all gflag arguments in ros_gz_sim::create with ROS parameters.

Test it

can try running following command
To launch gazebo sim:
ros2 launch ros_gz_sim gz_sim.launch.py
To spawn a model:
ros2 run ros_gz_sim create --ros-args -p world:=”default” -p file:='https://fuel.ignitionrobotics.org/1.0/openrobotics/models/Gazebo'

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

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[ahcorde]

Do you mind to sign the commit ?

[ahcorde]

Suggested change

	// declaring ros param
	ros2_node->declare_parameter("world","");
	// declaring ros param
	ros2_node->declare_parameter("world","");

[yaswanth1701]

Yeah I can do that, sorry this was my first time and forgot to do that before. I will make the changes and will push again.

[ahcorde]

In general we use underscore at the end when the variables are attributes of class, do you mind to remove the undercore at the end of tha variable name ?

Suggested change

	std::string world_,file_,param_,string_,topic_,name_;
	bool allow_renaming_;
	double x_,y_,z_,R_,P_,Y_;
	std::string world_, file_, param_, string_, topic_, name_;
	bool allow_renaming_;
	double x_, y_, z_, R_, P_, Y_;

[yaswanth1701]

Hi @ahcorde , I have made the changes could you please review again. Thank you.

[azeey]

We have a PR similar to this in #465. That PR does not remove the gflags processing, so I'd be in favor of closing this and reviewing that.

[yaswanth1701]

Hi @azeey yes, you can close this PR. There are few issues with my PC , So didn't got chance to work on this again, sorry for the trouble.

[azeey]

Okay, thanks for your contribution though!