add optional native Linux title bar setting

[ptdewey]

Adds a Linux-only appearance setting to use the native window-manager title bar instead of the default electron title bar. This option will only show up in the settings page on a linux system, and requires a restartn to take effect (the electron window needs to be recreated to adjust window decorations). Default behavior remains the same as before.

Screenshots:

With default electron title bar:

No title bar (based on my window manager setting):

Toggle in settings:

Sorry if I should have opened an issue for this first, but I figured this would a relatively small and unobjectionable change.

[wholetthekfcgo]

+1

[radiorambo]

Fixes #263

[raphael-soares]

+1

[Kamyil]

omg, I would love to have this on macOS as well. Default title bar takes so much space, I would like to have something like Helium browser has

[Tornado300]

yes please. that would be awesome!.

[Tornado300]

for everyone that wants to have a quick fix/workaround for removing the title bar, you can just remove the whole bar with css.

.glass-titlebar {
	display: none;
}

maybe that helps someone.

[Kamyil]

@Tornado300 Holy cow, it's soooo sooo much better. Thank you so much!

[Tornado300]

@Kamyil no problem, css overrides are powerful.
PS: if you are on the discord, there is a theme channel where everyone can put css snippets. i have also put a snippet for better tabs. it makes them a bit bigger, rounder, changes the limiter bar and some other stuff. im also doin some other snippets and might post them there if they are worth it.