Better coordination & communication among our different platforms

• We need to make sure to coordinate among ☁ server, 🤖 Android, 🍏 iOS & 💻 desktop.
• New features should be centrally discussed in the server repository. (For example the updated share flow, or the QR code to sign in → they are all related to all platforms.)
• Get people from desktop and mobile involved directly because the web interface should follow patterns which apply to mobile & desktop too. @-mention @nextcloud/desktop @nextcloud/android @nextcloud/ios
• Mobile and desktop people can add the issue to their relevant project boards. (Issues can be assigned to multiple projects).
• We use issue tags "client: 🤖🍏 mobile" and "client: 💻 desktop" in the server repository these cross-platform issues.

All issues are labeled "overview" and "client: 💻 desktop" and "client: 🤖🍏 mobile" and can be found here