enhance: close all windows with ESC

[NathanBaulch]

My muscle memory expects dialogs to be easily dismissed with ESC, so it's quite jarring when it doesn't work.
This PR ensures all chromeless windows close when escape is pressed.

[love-linger]

I do not like this PR. ESC should only close toolbox windows (normally a modal dialog). Windows like File Histories, Blame, Branch Compare and Dir Histories should not use ESC to close.

[NathanBaulch]

AFAIK none of these windows have unsaved state that the user needs to commit, so what's the risk of providing a quick dismiss option? Nothing is lost if the user accidentally hits ESC.

[love-linger]

This has nothing to do with the content displayed within the window, but only with the window's own displaying mode.

Usually, if a window is independent of another window, has Minimize and Maximize buttons, and has Actived and Deactived states, the ESC key will not be used to close the window.

For example: on macOS, we use system caption buttons instead of the custom CaptionButtons view. When pressed the green button, the window will be changed to full-screen mode. And then user restore it using ESC key.