Drop ROS 1 support; add ROS 2 Kilted

[lreiher]

• drop ROS 1 nodelet implementation and plugin
• simplify build and package files for ROS 2 only
• update CI and docker workflow to only test ROS 2 and add Kilted
• update docs and README to remove ROS 1 references and mention Kilted

[Copilot]

Pull Request Overview

This PR removes all ROS 1 support and refactors the packages for ROS 2 only (now including Kilted), bumps package versions to 2.4.0 with updated changelogs, and updates documentation and CI workflows accordingly.

• Drop ROS 1 nodelet implementation, launch files, and related build logic
• Bump versions to 2.4.0 and add changelog entries for ROS 2 Kilted
• Update docs, README, and GitHub workflows to reference ROS 2 only

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
mqtt_client_interfaces/package.xml	Bumped version, removed ROS 1 conditionals, unified ROS 2 deps
mqtt_client_interfaces/CMakeLists.txt	Removed ROS 1 build blocks, kept ROS 2 ament_cmake setup
mqtt_client_interfaces/CHANGELOG.rst	Added 2.4.0 entry
mqtt_client/package.xml	Bumped version, removed ROS 1 dependencies
mqtt_client/nodelet_plugins.xml	Removed obsolete ROS 1 nodelet plugin configuration
mqtt_client/launch/standalone.launch	Removed ROS 1 launch file
mqtt_client/doc/mainpage.dox	Updated description to ROS 2 component node
mqtt_client/CMakeLists.txt	Stripped ROS 1/Catkin logic, ROS 2 only build
mqtt_client/CHANGELOG.rst	Added 2.4.0 entry
README.md	Updated badges, install/launch instructions for ROS 2 only
.github/workflows/industrial_ci.yml	Added “kilted” to ROS 2 matrix
.github/workflows/docker-ros.yml	Removed the ROS 1 docker job

Comments suppressed due to low confidence (3)

mqtt_client/nodelet_plugins.xml:1

• This file is now empty after dropping ROS 1 support; consider deleting the obsolete nodelet_plugins.xml to avoid confusion.

<library path="lib/libmqtt_client">

mqtt_client/launch/standalone.launch:1

• Since this ROS 1 launch file has been fully removed, you may want to delete standalone.launch entirely rather than leaving it empty.

<launch>

README.md:113

• The README references standalone.launch.ros2.xml, but I don't see that file added here; please ensure the correct launch filename is used or include the new launch file.

ros2 launch mqtt_client standalone.launch.ros2.xml