Added visibility to interactions to the UI along with callbacks to tr…

[JaschaW]

Description of Changes

This update adds a visibility control icon to each item in the Guide UI.
The UI now includes per-item display toggles that are clickable and fully interactive, allowing users to control visibility directly from the interface.

Supporting logic was implemented to handle display state changes, along with callbacks to ensure the UI remains synchronized with the guide elements in the Maya scene at all times.

In addition, a new mGear-specific icon was added for this tool. This change was made because the default Maya icons were not consistently available across different machines. The new icon has been integrated into the existing mGear icon library to ensure reliable and consistent display.

Testing Done

• Verified that visibility icons appear correctly for each guide item in the UI
• Confirmed that toggling visibility from the UI correctly updates the corresponding objects in the Maya scene
• Confirmed that scene-driven visibility changes are reflected back in the UI via callbacks

Related Issue(s)

N/A