Use separate repository for the simulation world Small House

[samuelgundry]

Small House world is now a ROS package in separate github repository. It is not published to the ROS package repository so we clone the source.

Note the ROS package name has changed from aws_robomaker_simulation_small_house to aws_robomaker_small_house_world.

The source is cloned via rosws:

cd simulation_ws
rosws update

This clones into simulation_ws/src/aws-robomaker-small-house-world. This is configured in the .rosinstall file.

Building and bundling works as before:

rosdep install --from-paths src --ignore-src -r -y
colcon build
colcon bundle

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.