Add dependencies for ros1-bridge demos

[mikaelarguedas]

This is a follow up of ros2/ros1_bridge#228

The bride images should provide the packages providing talker and listener in their ROS 1 and 2 form for basic testing / tutorial to be possible out of the box

[ruffsl]

I like the idea. How much does this increase the size of the bridge image?
I'm guessing the demo's rope in a lot of extra packages though.

[mikaelarguedas]

Apparently 12MB of extra disk space:

The following additional packages will be installed:
  ros-eloquent-example-interfaces
The following NEW packages will be installed:
  ros-eloquent-demo-nodes-cpp ros-eloquent-demo-nodes-py
  ros-eloquent-example-interfaces
0 upgraded, 3 newly installed, 0 to remove and 16 not upgraded.
Need to get 1008 kB of archives.
After this operation, 12.2 MB of additional disk space will be used.

The ros1-bridge deb already pulls in the ros1 tutorial packages (ros2/ros1_bridge#228)

[mikaelarguedas]

Given the very limited footprint of this and the benefit for tutorials and consistency I'm going to go ahead and integrate this.