Sensors and Events for Hands -vs- Controllers

[AtifMahmud]

Description

Incrementally building towards hand tracking support, we are sending sensors for whether participant is using hands, controllers, or none. We are also sending events when they switch between hands and controllers.

For the sensors:

• 0 = None
• 1 = Controller
• 2 = Hand

Session with example: https://app.cognitive3d.com/scenes/3fdf2fd6-4d2d-405b-b638-d6d619ebcc96/v/19/session/1201395 https://github.com/CognitiveVR/cvr-sdk-unity/assets/14244062/d8221a17-4303-4f78-bf47-8ddbdf2aa87b

Height Task ID(s) (If applicable): https://c3d.height.app/T-4643

Type of change

• [x] New feature (non-breaking change which adds functionality)
• [x] This change requires a documentation update

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] My changes generate no new warnings
• [ ] Any dependent changes have been merged and published in downstream modules
• [x] I have assigned this PR to myself in GitHub
• [x] I have assigned and notified Reviewers for this PR