Reduce fear and confusion during upgrades (prompt user when upgrade is about to start)

[tristanbob]

Description

Many users have reported on Discord that GDevelop upgrades can be scary due to uncertainty and unexpected behavior.

Currently, upgrades happen when the user first opens GDevelop. They see the app open briefly and then it appears to crash and closes itself. When the user tries to immediately re-open the application, they may discover that the shortcut no longer exists. Panic is a common emotion at this point.

Shortly after, GDevelop completes the upgrade and the user can use the application again. The user is temporarily relieved, even though this same experience awaits them on the next upgrade.

Solution suggested

• When an upgrade is about to take place, inform the user: "GDevelop version X.Y.Z is available. Do you want to start the upgrade?"

• Provide text explaining what to expect "GDevelop will not be available during the upgrade. Please wait a minute after the upgrade starts before opening GDevelop."

[Silver-Streak]

I can see a lot of value of making the auto-update a prompt rather than forced, especially since it lets the developers control how it appears to the user, and allows the user to decide whether to upgrade or not.