Support additional hand image compression

[sktometometo]

Reflecting k-okada/spot_ros-arm#4 change and publish compressed rgb and depth image for hands.

[sktometometo]

@k-okada Please also merge this

[k-okada]

Plaese check the CPU usage rate. I am concerned that the CPU utilization may become unnecessarily high for a series of partial PRs.
(1) I would originally like to use connectionbasedtransport, but I think the dependency on spot->jsk is too much work, so I would like to put in a similar process and fetch images from inside the body only when necessary.
2) Since it seems that JEPG images can be retrieved using SpotSDK, only compressed images should be published in the first place.
https://dev.bostondynamics.com/python/bosdyn-client/src/bosdyn/client/image#bosdyn.client.image.build_image_request

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