Adds a Gripper Depth Overlay

[hello-amal]

Description

This PR adds a gripper depth overlay, which highlights points within the graspable region.

Testing procedure

• [x] On a Stretch with the D405:
  • [x] Click depth sending under the gripper camera, verify it works.
  • [x] Verify it doesn't significantly worsen the latency. (If did, but see #61 for the fix.)
  • [x] Uncheck it, verify it works.
  • [x] Verify the highlighted points are actually in the graspable region.
  • [x] Use it with click-to-pregrasp, for both horizontal and vertical grasps. Verify it helps to grasp objects.
• [x] Attach a tablet and switch the tool using stretch_configure_tool.py, verify that the depth sensing feature does not appear on the web app.
• [x] On a Stretch with the beta teleop kit:
  • [x] Verify the "Depth Sensing" option does not appear below the gripper camera.

Before opening a pull request

From the top-level of this repository, run:

• [ ] pre-commit run --all-files

To merge

• [ ] Squash & Merge