add source entry for new package conditional_substitution

[ottojo]

Please Add This Package to be indexed in the rosdistro.

This package provides a single utility function for choosing substitutions in a launch file depending on a condition.

The source is here: https://github.com/ottojo/ros_conditional_substitution

Checks

• All packages have a declared license in the package.xml
• This repository has a LICENSE file
• This package is expected to build on the submitted rosdistro

[clalancette]

New package review checklist

You can copy-paste the below into your review comment when reviewing a new package addition into rosdistro.

• At least one of the following must be present
  • Top level license file: https://github.com/ottojo/ros_conditional_substitution/blob/43819308a242fd3cfce9b28acf04fb885723cf4f/LICENSE
  • Per package license files:
• License is OSI-approved: MIT
• License correctly listed in package.xmls
• Public source repo: https://github.com/ottojo/ros_conditional_substitution
• Source repository contains ROS packages (though https://github.com/ottojo/ros_conditional_substitution/blob/43819308a242fd3cfce9b28acf04fb885723cf4f/setup.py#L18 could be updated)
• Each package meets REP-144 naming conventions: I'm not sure about this one. The name here is really generic, so I think violates Global Guidelines bullet 1 and possibly bullet 4. Also, can you please explain how this differs from Add conditional substitution ros2/launch#734 ?

[ottojo]

It does not differ at all from ros2/launch#734, which is why i opened ros2/launch#776 and converted this back to draft. I only opened this because i didn't know about the implementation in launch, which so far is only available in rolling i think, and which i only discovered just after opening this 🙃

[clalancette]

All right. In that case, I'm going to go ahead and close this since we can get the same functionality from that PR.