clean and merge ros1 and ros2 cmakelists and package

[rafa-martin]

This pull request includes significant updates to support both ROS and ROS2 environments in the rslidar_msg project. The most important changes include modifications to the CMakeLists.txt and package.xml files to conditionally handle dependencies and configurations for ROS and ROS2, as well as cleanup of redundant files.

ROS and ROS2 Support:

• CMakeLists.txt: Added conditional support for ROS and ROS2, including finding necessary packages, generating messages, and setting appropriate C++ standards.
• package.xml: Updated dependencies and configurations to conditionally support ROS and ROS2, including build tool dependencies and message generation/runtime dependencies.

Cleanup:

• Removed redundant ros1 and ros2 directories, including their CMakeLists.txt and package.xml files, as their functionalities are now integrated into the main CMakeLists.txt and package.xml. [1] [2] [3] [4]

Documentation:

• README.md: Minor formatting cleanup.