Feature: Add window transparency for linux

[lyimmi]

This PR resolves #1923 by implementing window transparency on linux.

• Added transparency in v2/internal/frontend/desktop/linux/window.go
• Created WindowIsTranslucent option in v2/pkg/options/linux/linux.go
• Updated docs in website/docs/reference/options.mdx

Tested on:

• Linux/amd64, PopOs 22.04 with X11 (In this case its the same as Ubuntu 22.04)
  • Works as intended.
• Linux/arm, Raspbian GNU/Linux 11 (bullseye)
  • It does not work on raspbian, because the window manager doesn't supports compositing, but the case is handled, so the window opens as opaque.

[leaanthony]

Nice one!