Support disabling the screen blank/lock

[andydotxyz]

API proposed and implementation for iOS and Android.
Windows/macOS/Linux X11&Wayland could be another PR?

Fixes #4534

Checklist:

• Tests included.
• Lint and formatter run with no errors.
• Tests all pass.
• Public APIs match existing style and have Since: line.

[coveralls]

coverage: 64.601% (-0.02%) from 64.625%
when pulling c16afc6 on andydotxyz:feature/blockscreenlock
into 4f617dc on fyne-io:develop.

[dweymouth]

Should this really be a desktop API as well? Isn't asking the screen not to sleep pretty much a mobile-only thing?

At a minimum, if we want this to be an all-platform API it should probably be RequestDisableScreenBlanking or similar, to reflect that some OSes/DEs may refuse the request or not support it at all

[andydotxyz]

I was going on what the linked issue described - the way that macOS, Windows and Linux allow apps to stop screensaver in the same way the mobile stops the screen switch off / lock.

to reflect that some OSes/DEs may refuse the request or not support it at all

I've not found one that can block this request yet.

[dweymouth]

I was going on what the linked issue described - the way that macOS, Windows and Linux allow apps to stop screensaver in the same way the mobile stops the screen switch off / lock.

to reflect that some OSes/DEs may refuse the request or not support it at all

I've not found one that can block this request yet.

Ah, OK, hadn't seen the latest comment activity on the ticket. I'd say if we can at least verify that we can support it on Windows, Mac, and X11, then we can go with the Set... naming as proposed in this PR. The actual implementation could wait until a follow-up PR

[dweymouth]

I think this is good to go now, as long as we remember to add the desktop implementation before pulling it into a release

[andydotxyz]

Thanks, I opened #4567 to remind us about desktop, and added it to 2.5 milestone