[rolling] image_publisher: add field of view parameter

[Kotochleb]

Currently, the default value for focal length when no camera info is provided defaults to 1.0 rendering whole approximate intrinsics and projection matrices useless. Based on this article, I propose a better approximation of the focal length based on the field of view of the camera.

For most of the use cases, users will either know the field of view of the camera the used, or they already calibrated it ahead of time.

If there is some documentation to fill. please let me know.

This PR should be straightforward to port it to Humble, Iron and Jazzy.

[Kotochleb]

@ahcorde the changes were retargeted to rolling as requested, plus I added documentation for the new parameter since this branch accounts for that.

[ahcorde]

https://github.com/Mergifyio backport jazzy humble iron

[mergify[bot]]

backport jazzy humble iron

✅ Backports have been created

* [#992 [rolling] image_publisher: add field of view parameter (backport #985)](https://github.com/ros-perception/image_pipeline/pull/992) has been created for branch `jazzy` * [#993 [rolling] image_publisher: add field of view parameter (backport #985)](https://github.com/ros-perception/image_pipeline/pull/993) has been created for branch `humble` but encountered conflicts * [#994 [rolling] image_publisher: add field of view parameter (backport #985)](https://github.com/ros-perception/image_pipeline/pull/994) has been created for branch `iron` but encountered conflicts