Rebase with latest OpenVINS

[mhuzai]

This is not high priority, but getting all the latest features from rpng/open_vins would be good, whenever we have the time.

[xloem]

Are any of your changes upstreamable to ease maintenance in the future?

Additionally if loop closure from VINS-Fusion could be brought up-to-snuff in the rpng repository then they would keep the setup maintained.

[mhuzai]

Our changes are mostly related to performance profiling and integration with the ILLIXR runtime, so I don't think upstreaming them will be possible.

Not sure I understand the loop closure comment.