ros2: failed to load plugin theora_pub

[kervel]

Hello,

When trying theora in ROS2, we get

Failed to load plugin image_transport/theora_pub, error string: Could not find library corresponding to plugin image_transport/theora_pub. Make sure the plugin description XML file has the correct name of the library and that the library actually exists.

this was actually reported here first: ros-perception/image_common#113

I think this is due to a simple error in theora_plugins.xml. In the xml file, the path of the library is defined as "lib/theora_image_transport", but in the CMakeLists, the library is called theora_image_transport_component.

Changing the path to simply "theora_image_transport_component" (without the lib/) fixes the error.

Frank

[kervel]

PR #38