Airflow/Wind sensor

[henrykotze]

🎉 New feature

Summary

This adds an airflow sensor. These sensors are generally used to measure wind and are ultrasonic devices, measuring the airflow speed and direction using the Doppler effect.

Depends on:

• https://github.com/gazebosim/sdformat/pull/1349
• https://github.com/gazebosim/gz-msgs/pull/411

Here is some use cases of such sensors from a manufacturer sensor which we have used. https://fttechnologies.com/case-studies.

This is part of a larger plan to support an airflow sensor in PX4. @dagar

The code is heavily based on the Airspeed Sensor

##Test it

Test are added to ensure correct use. Checklist

Signed all commits for DCO Added tests Added example and/or tutorial Updated documentation (as needed) Updated migration guide (as needed) Consider updating Python bindings (if the library has them) codecheck passed (See contributing) All tests passed (See test coverage)

While waiting for a review on your PR, please help review [another open pull request](https://github.com/pulls?q=is%3Aopen+is%3Apr+user%3Agazebosim+archived%3Afalse+) to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.