Add support for blocking screenshots from being taken

[grrrrr]

I am aware that this is not a perfect privacy solution and there are ways around it but it would be useful to have Material Files block the ability to take screenshots.

While the risks / concerns of someone remotely taking a screenshot of Material Files on most peoples devices phone are low there are still users who are high risk, it is a possibility that some malware is setup to take screenshots of open apps and in this instance potentially record listing of phone storage

Additionally with screenshots blocked, switching apps would result in you seeing Material Files is your list of open apps but not seeing the screen it's contents

My suggestion would be to add a toggle allowing users to opt-in to this feature, and could be added to the Settings -> behavior section.

Some apps that do that have this option if examples/comparison is needed

• KeepassDX (always blocked)
• Signal (allows toggling screenshot capture on or off)
• ProtonMail (allows toggling screenshot capture on or off)
• Aegis (allows toggling screenshot capture on or off)
• MediLog (allows toggling screenshot capture on or off)