Find typesupport libraries in LD_LIBRARY_PATH

[adityapande-1995]

Description

As per https://github.com/ros2/rosbag2/blob/0f3ebfe61783b35348fa642cc50b30e2a6c5163f/rosbag2_cpp/src/rosbag2_cpp/typesupport_helpers.cpp#L51-L58, rosbag looks for message typesupport libraries in the "lib/" directory relative to the package in the ament prefix path. This means that the recorder machine should have the typesupport libraries available in that location only, and assumes that the message package is a ros package, and that it exists in the ament prefix path.

When using other build systems like bazel, there may not be a ament prefix path, and the libraries might be available on the standard LD_LIBRARY_PATH. There should be a way to look for the libraries in the LD_LIBRARY_PATH as a backup, if they are not found in ament prefix path.

Completion Criteria

Typesupport libraries can be picked up from LD_LIBRARY_PATH if not found in ament prefix path.

[fujitatomoya]

@adityapande-1995 out of curiosity,

When using other build systems like bazel, there may not be a ament prefix path

bazel is officially supported? there are many build tools...