Create proper Menu Icons

[Dat-Pudding]

What needs to be done?

Proper/better icons for the menu buttons need to be made and added. Either just as an asset in the repo or already implemented into the app project(s).

What are the requirements?

• must be text-free and interculturally/universally understandable
• resolution per icon must be at least 1024x1024
• must be 16-bit RGBA
• refrain from using blue or green colors
• has to be centered in a square or tiled in equal squares on an icon sheet
• ideally with *.svg added in the pr

Checklist

• Icon for "Exposure time calculator"
• Icon for "Field of View calculator"
• Icon for "Solid white for flat frames"
• Icon for "Camera database interface"
• Icon for "About Page"
• Icon for "Back to main menu"