Add support for bridging NavSat

[TyHowellWork]

🎉 New feature

Closes #218

Summary

Adds two-way bridge for NavSat messages between ROS and IGN along with a demo launch file.

Test it

Test IGN->ROS by running roslaunch ros_ign_gazebo_demos navsat.launch.
Test ROS->IGN by roslaunch ros_ign_gazebo_demos navsat.launch and ign topic -t /navsat -e

rostopic pub -r 1 /navsat sensor_msgs/NavSatFix "header:
  seq: 10
  stamp: {secs: 10, nsecs: 0}
  frame_id: 'back_to_ign'
status: {status: 0, service: 0}
latitude: 10.0
longitude: 10.0
altitude: 10.0
position_covariance: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
position_covariance_type: 0"

Even using the contributing guides I was unable to get codecheck or the tests running :(

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• 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 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.

[chapulina]

Thanks for the PR. The implementation, test and example look great!

The only catch is that this branch is supported with both Citadel and Fortress, but the NavSat message and the NavSat sensor are only available from Fortress. So we have a couple of options:

• Add ifdefs so the NavSat is only present on IGN_MSGS_VER >= 8
• Or backport the NavSat message to ign-msgs5 - while this is trivial, backporting the NavSat sensor itself isn't. It shouldn't hurt having the message there though.

In any case, we should add a note to ros_ign_gazebo_demos/README.md that the GNSS example only works from Fortress.

[TyHowellWork]

@chapulina @ahcorde Thanks for the reviews I should have a fix :) by the end of the day.

[TyHowellWork]

ign-msgs5 PR has been submitted that backports NavSat message only.

[chapulina]

ign-msgs5 gazebosim/gz-msgs#231 has been submitted that backports NavSat message only.

Thanks! Here are the next steps:

• Release ign-msgs5 with the NavSat message: 🎈 5.9.0 gz-msgs#232
• Pull that into packages.ros.org with reprepro
• Run CI on this PR

[chapulina]

Ready! Thanks for the wait!

addressed