Implement libinput device configuration

We need to defer config application to the first manage_start event
using a should_manage flag so that all *_support events have arrived
before we try applying the configs

This commit also has two other fixes
- fixes a potential use-after-free by telling InputDevice when a
 LibinputDevice is .removed.
- fix logFn (removed "if (scope != .default) return;")

I used kwm to help figure out the manage pattern for the input config.
Link to kwm: https://github.com/kewuaa/kwm

README.md

@@ -10,14 +10,20 @@ SPDX-License-Identifier: GPL-3.0-or-later
 
 These are in rough order of my priority, though no promises I do them in this order.
 
+- [ ] Support `None` modifier for keybinds (needed for media/brightness keys)
 - [ ] Support per-host config using properties (maybe also per-output?)
 - [ ] Add input configuration, i.e. pointer acceleration and that type of thing
 - [ ] Support a basic bar
 - [ ] Support starting programs at WM launch
 - [ ] Support overriding config location
 - [ ] Add support for multimedia/brightness keys (this might not be neccesary)
+- [ ] Support window rules (float/tags/SSD by app-id/title)
+- [ ] Support switch handling (e.g. lid close)
 - [ ] Support multiple seats
 - [ ] Support clipping floating windows on edge of/between outputs
+- [ ] Support keybind modes (e.g. passthrough)
+- [ ] Support `focus-follows-cursor` granularity (`normal` vs `always`)
+- [ ] Support solid `background-color` fallback (no wallpaper)
 - [x] Support changeable primary ratio
 - [x] Support changeable primary count
 - [x] Support multiple outputs