cmd_bind{sym,code}: Implement per-device bindings

[RedSoxFan]

Closes #2378
Closes #2141

Implements the syntax bind{sym,code} --input-device=<identifier> <...> for both keyboard and mouse bindings.

Since I don't have multiple physical keyboards, I found this easiest to test by launching sway on DRM, on the Wayland backend, and on the X11 backend.

My test config:

set $mod Mod4
set $keyboard <keyboard-id>
set $wl_keyboard 0:0:wayland
set $mouse <mouse-id>
set $wl_mouse 0:0:wayland

bindsym $mod+x exec urxvt -e python
bindsym --input-device=$keyboard $mod+x exec urxvt -e bash
bindsym --input-device=$wl_keyboard $mod+x exec urxvt -e zsh

bindsym --whole-window button3 floating toggle
bindsym --input-device=$mouse --whole-window button3 fullscreen toggle
bindsym --input-device=$wl_mouse --whole-window button3 border toggle

For the config above:

• urxvt -e python and floating toggle should get triggered on the X11 backend
• urxvt -e bash and fullscreen toggle should get triggered on DRM
• urxvt -e zsh and border toggle should get triggered on the Wayland backend

[ddevault]

neat

[ianyfan]

I think you should add a property to the ipc binding event for this.

[ddevault]

Sure, but it could be a separate patch.

[ddevault]

Thanks!