[feature] Pass extra parameters to Xacro on the URDF Preview

[danieto98]

what is needed
Allow the ROS: Preview URDF command to relay substitution arguments to the xacro command.

why is it needed
When attempting to preview a URDF/Xacro file that makes use of the Rospack command $(arg ...) inside of it, the preview command fails. The current workaround is to manually update the file to replace those arguments before doing the preview, but this is quite tedious and error-prone.

[ooeygui]

Thank you for the feature request.
Need to think through the UI for this. Can you suggest how you would expose it?

[danieto98]

I think for most cases a UI is not necessary, just a way to specify these substitution arguments so that they are appended to the xacro command would be enough. This could be in a config file, or even in the extension settings so they can be written to the settings.json.