Refactor CI workflows and devcontainer configuration for improved cla…

[marc-hanheide]

This pull request updates the development and CI environment configuration to improve flexibility and consistency, especially regarding ROS distribution selection. The changes primarily focus on parameterizing the ROS distribution in workflows and devcontainer settings, making it easier to switch between different ROS versions (like "humble" or "iron") without modifying multiple hardcoded values. It also cleans up and modernizes some workflow files.

Key changes include:

Parameterization and Environment Consistency

• Replaced hardcoded references to the ROS distribution (e.g., "humble") with the ROS_DISTRO environment variable in both .github/workflows/build-docker.yml and .github/workflows/copilot-setup-steps.yml, allowing easier switching between ROS versions. [1] [2] [3] [4]
• Updated installation, setup, and build steps in workflows to use ${ROS_DISTRO} instead of fixed values, ensuring consistency across all scripts and jobs. [1] [2]

Devcontainer and Workflow Improvements

• Changed the devcontainer name from "ROS 2 Humble Devcontainer" to "ROS 2 Devcontainer" in .devcontainer/devcontainer.json for broader applicability.
• Modified .github/workflows/dev-container.yml to trigger on changes to devcontainer-related files, not just on pushes to the main branch, improving CI relevance.

Metadata and Workflow Cleanup

• Added the creator label to Docker image metadata for better traceability in .github/workflows/build-docker.yml.
• Upgraded the actions/checkout action from v3 to v6 in .github/workflows/ros-ci.yml for improved security and features.
• Removed commented-out and unused configuration for additional ROS distributions and versions in .github/workflows/ros-ci.yml, simplifying the workflow. [1] [2] [3]