Improve documentation and simplify working in Docker

[victorreijgwart]

This PR makes no functional changes to wavemap or its ROS interfaces.

Instead, it focuses on improving:

• The documentation
• The ease of installing wavemap, by including Docker as an alternative install method

Detailed changes:

• Improve the automatic documentation generation, hosted on GitHub Pages:
  • Fix doxygen relative source file path resolution errors
  • Configure Sphinx to check the validity of all outgoing links; incl. a helper script
  • Automatically update the package version embedded in the docs by parsing wavemap's package.xml
• Clean up the main README and move the documentation it contained to the main docs
• Adds a Docker file to perform fast builds that are still optimized for the host machine's architecture, by pulling a base image from Continuous Deployment with pre-compiled dependencies and only compiling wavemap itself locally (where the exact machine architecture is known).
• Add instructions on how to use wavemap with Docker to the README, including an example run script with detailed comments

[victorreijgwart]

/prepare-release minor

[github-actions[bot]]

Preview of release notes will be added here.

[victorreijgwart]

This PR was discussed and reviewed in person. Thank you @LionelOtt!