some mice have a per axis "sensitivity" control which adapts the hardware
resolution without changing the DPI (looking at you Etekcity and Roccat).

buttons need a couple of has_capability() functions to check which action
types and actions are possible

light support:
- on/off
- color
- patterns

some epollfd-like thing for the caller to check if events are available.
Needed for notification when the mouse changes through someone else
manipulating settings.
This is on backburner for now, it'll make the library more complicated,
require HID parsing in libratbag for relatively little benefit. The only
advantage we really get out of it is that a configuration UI would be able
to update itself if a user presses a button to e.g. change the profile while
the UI is running.

Macro support:
- enhance doctext
- add API support for name/groups
- revamp the API?
- add command to set a macro in ratbag-command