Switch off icon visibility

### User Story Description

As a SAF customer, I want to be able to control if an icon in the bottom tray does not show up. This can be done via either a direct call, or by using the state mechanism to control widget visibility.

### Acceptance Criteria

VISOR can be started with the "full screen" icon not available.

### Additional Links

_No response_

### Requires new or update to third party ? If "yes" add the name(s) and the version(s) of the Third Party Software.

No

### Name and Version for Third Parties

_No response_

Start by locating the bottom-tray widget that renders the full-screen icon and the state mechanism used to control widget visibility. Check how VISOR is initialized and determine how a direct call or visibility state can hide the icon; done means VISOR can start without the full-screen icon while the remaining tray continues to work.

Scritto dal modello di indicizzazione a partire dal testo della issue.