Add Screenshot button

[danirabbit]

Proof of concept for taking screenshots from quick settings using the portal. This would replace the current screenshot app.

Todo:

• Actually save the screenshot to screenshots
• Fix the application sender so that notifications show a screenshot icon badge
• Provide a .desktop with the screenshot app's actions
• Add a copy to clipboard action?
• Review other feedback from Notification workflow screenshot#253

[danirabbit]

Since we need a .desktop anyways to do a lot of this stuff, perhaps we do still need the screenshot app to be a separate app

[danirabbit]

I'm going to close this since this doesn't seem to really be an improvement. It would be a better direction to make the screenshot app use the portal

[leolost2605]

I think this would actually be really cool. Since I'm a student my workflow when summing up lectures usually is that I have my 2 in 1 in tablet mode and my browser and my handwritten note taking app side by side open. Then I often have to take screenshots of some parts of the lecture notes provided by my profs and paste them into my note taking app for anotation. This can get pretty exhausting because opening an app especially without keyboard is usually much more work than clicking a little button of which I exactly know where it is. So I think a button would definitely be nice here. Whether that just launches the app or does it here can be argued about I guess.