sensor.proto: use NavSatSensor type

[scpeters]

🦟 Bug fix

Follow-up to #476. Needed by gazebosim/gz-sim#2910.

Summary

There are separate navsat.proto and navsat_sensor.proto messages. All the subfields of sensor.proto use _sensor.proto messages, except for navsat, which I assume was a typo in #476. This changes the navsat field from NavSat type to NavSatSensor type.

The Migration guide doesn't need to be changed.

Checklist

• Signed all commits for DCO
• Added tests
• 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 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.

[scpeters]

windows compiler warnings are pre-existing

• https://build.osrfoundation.org/job/gz_msgs-pr-cnlwin/28/
• https://build.osrfoundation.org/job/gz_msgs-main-cnlwin/12/

[scpeters]

rebuilding nightly deb:

• https://build.osrfoundation.org/job/gz-msgs12-debbuilder/77/