Add camera fullscreen view

[bdpdx]

Fixes #7272

I added a full screen camera view feature. This includes:

• A Settings option to view only on the current monitor (default) or on all monitors (blanking non-default monitors).
• ESC key to exit
  • MacOS required special handling, I didn't add anything extra for Windows or Linux
• Close button in upper right corner to exit full screen view (fades out after 5s, reappears on mouse movement).
• Menu item to 'Enter Camera Full Screen' under the View menu
• Localized to all supported languages

Note to maintainers:

I only tested it on MacOS as I don't have a Windows machine or Linux desktop available.

Please test on Windows and Linux.

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This is what the Settings dialog looks like now (see last entry):

This is the new camera view toolbar:

This is the full screen view: