Add rmw dependencies due to EventsExecutor PR in rcl

[JanStaschulat]

see issue #254

[JanStaschulat]

tried several things, but none of them worked:

• clone rmw repository and build one step before building rclc
• update ros-tooling/action-ros-ci version to 0.2.4
• added rmw to package-name

[christophebedard]

I think you can simply add rmw to the existing dependencies.repos file. You don't need to add rmw to package-name, since the source code will all be in the same workspace, and action-ros-ci runs colcon build --packages-up-to $package-name ....