Add vision subpackage with MediaPipe HeadTracker

[alozowski]

Adds a vision subpackage with the MediaPipe HeadTracker, migrated from reachy_mini_toolbox. Also, mediapipe==0.10.14 is added as a new optional extra. The original exit() on missing mediapipe is replaced with a proper ImportError to avoid killing the robot process on import

Closes #1175
The conv app PR: pollen-robotics/reachy_mini_conversation_app#381

[FabienDanieau]

Is it an issue to have reachy_mini_toolbox as a dep in the conv app?

[pierre-rouanet]

LGTM, indeed as @FabienDanieau points out. Maybe we can use toolbox as a dependency. Not strong opinion on this. Just if we do, we have to make sure that everything included runs on a RM wireless.

Maybe next step is ton add start/stop/getface API entry points to trigger the head tracking in background?

[FabienDanieau]

I made some tests. rf-detr-nano is too heavy for the rpi. Mediapipe seems to be the most suitable solution for edge devices. There is a lighter model that we can use instead of the facemesh of the tool box: see face_track.py.
We need to mind the numpy 1.x dependency though.

Maybe next step is ton add start/stop/getface API entry points to trigger the head tracking in background?

I agree with @pierre-rouanet, the right call would be to enable head tracking on the daemon side (in a way similar we did for the wobbling see #1001). Basically we need to add a appsink to the video pipeline to feed the head tracker.

Also the tracking could be extended with the DoA. But let's keep that for another issue :)

[HuggingFaceDocBuilderDev]

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[alozowski]

let's say that mediapipe works here though it's not ideal:
6c7a911

I'm continuing my experiment with completely another approach in this branch

[alozowski]

next checkpoint, commit 9a5b52f

• opencv works
• start the daemon from this branch
• enable headtracking with curl -s -XPOST localhost:8000/api/media/tracking/enable -H Content-Type:application/json -d '{}'
• disable it with curl -s -XPOST localhost:8000/api/media/tracking/disable -H Conte{} (truncated command, I know, but it works)