switch to "new chat" on blur

[traycold]

@simgunz : here is the code I'm using that switch to "new chat" when Teams PWA window loses focus. It is completely based on work of @janhalasa (in his fork). It is still not ideal, because whenever you change focus on another windows, even if the Teams window is visible (and maybe you are activevely reading its content), the "new chat" view is activated and you loose the content of the current chat. But at least it seems to provide notification. Hopefully Microsoft will improve the Teams PWA, never had so many issues with old retired native app.