More precise robot footprint

Recent partial discussion in strands-project/strands_navigation#127 and older discussion in strands-project/autonomous_patrolling#70

I've been running with this since yesterday, and it did improve navigation in tight spots a bit.
Now that I can see the output of `navigation_base`, I didn't notice any missed messages as feared by @BFALacerda, but that might be thanks to offloading the chest-obstacle stuff to the side-pc.

I'm creating this PR for discussion and also for others to try.