Add basic Preferences widget

[kraifpatrik]

Add basic preferences widget so users don't have to write their own from scratch. This should include:

• A floating "Preferences" window
• A scrollable list of categories on the left side
• Scroll pane with settings for the currently selected category on the right
• "Reset to default" button for the currently selected category - restores default values for all settings
• A search bar at the top for looking up settings by their name across all categories (substring match). (This one is probably going to be tough to implement. We can leave it for later.)
• Keybindings configuration system
• Save & load system for preferences
• A way to query current value of a setting with given name/ID

Source: CRYENGINE Sandbox 5.7.1