Gitpod: Let users confirm closing the IDE

[svenefftinge]

We should let confirm users closing the IDE. As many seem to be used to closing editor tabs with ctrl+w (see e.g. https://lacourt.dev/2019/03/07/#closing-files).
Maybe we get the key event before the beforeClose and can base the decision on that.

[meysholdt]

👍 took me more than a month to unlearn the CTRL-W reflex.

[jankeromnes]

👍 I know many people who can't use cloud IDEs because they compulsively hit Ctrl+W all the time.

[svenefftinge]

fixed in theia

[MangelMaxime]

Hello,

for me if I press Ctrl+W, the browser tab is closed directly without any prompt.

I am using Chrome Version 80.0.3987.87 (64 bits) under Windows 10.

[hoegertn]

Same here on Chrome and macOS