Better fresh install workflow

Niri will now create a config file if it's not present, filling it with the default config contents. It will notify about this with a new message.

• Before, on a fresh install:

  

• After, on a fresh install:

  

wlr-foreign-toplevel-management

I've implemented the wlr-foreign-toplevel-management protocol used by taskbars like the wlr/taskbar Waybar module or sfwbar, and by some other clients like fcitx5.

Output rotation

You can now rotate and flip outputs with a new setting:

output "eDP-1" {
    // The rotations are counter-clockwise:
    transform "90"
}

Thanks @axtloss for implementing this and to @cmeissl for fixing various Smithay issues that had come up with transforms!

Other improvements in this release

• Keyboard LEDs (Num Lock, Caps Lock, Scroll Lock) will now light up. Thanks @cmeissl!
• Added move-workspace-to-monitor-{left,right,up,down} actions that move the entire workspace to a different monitor. They are not bound to any key by default (yet?). Thanks @Trundle for implementing this!
• Fixed semitransparent border and focus ring colors.
• Fixed natural-scroll not being respected for the touchpad workspace switch gesture.
• Fixed windows being unable to open in fullscreen mode right away.
• Monitor screencasts will now stop on monitor size changes. In the future it may be possible to resize the stream on the go but we don't do that yet, so just stop them to avoid wrong video frames.
• Fixed building on Rust 1.72.0.
• Made backend initialization errors more detailed.
• Fixed a panic when closing niri running as a nested window during a screen redraw.