Inventory Favorites Main Inventory Mockup

[akleshchev]

Description

Implement inventory favorites according to provided mockups. Branch: https://github.com/secondlife/viewer/tree/project/inventory_favorites

### Tasks
- [x] Implement Inventory Favorites Stars
- [x] Implement Context Menu items
- [x] Implement Framework
- [x] Update Places Floater
- [x] Update Settings
- [x] Update Gear Menu Items
- [x] Update inventory Settings

[kylelinden]

Work on Inventory Favorites in a branch for reviews and then pull into whichever maint makes sense.

[akleshchev]

Done in inventory_favorites branch, waiting for other favorite related changes before merging into a proper branch