Frameless window

[alepop]

Make app window more 💅

• Add frameless window
• Polish loading bar (I think now the best position is at the bottom of the window)

Before:

After:

[slaweet]

Thanks, @alepop, the frameless window looks really cool. 👍
Though, I noticed that pop-up toast notifications are not going all the way to the screen in this PR:

Before it looked like:

Also, did you check if there are no other side effects on Windows and Linux?

[alepop]

@slaweet ok, i will fix the pop-up. What about loading bar?
I can not test on Win or Linux 😞

[Isabello]

On windows there is no head bar which means there are no drop down menus. Additionally, removing the header on windows makes text unselectable on windows and instead moves the whole window when you try to select the test

We need the header to be present on windows and for the behavior to be as it was for text selection

[alepop]

@Isabello sounds bad. Maybe set frameless window only for macOS? Need core team decision.

[slaweet]

makes text unselectable on windows and instead moves the whole window when you try to select the text

This happens also on Mac OS