attempt to detect child windows

[koekeishiya]

Some changes were recently introduced in #2036 that makes yabai not detect and track windows that do not report as what is defined as a "real window". After some testing I feel like this alone is not the correct approach.

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Firstly we should detect whether or not the created window is a "root window" or a "child/sub window". Only windows that report as a "root window" will be eligible target for window rules, tiling, and focus follows mouse. Windows that do not identify as a "root window" will be tracked, but they will not be targeted by window rules and they will never be tiled (not even through force) or focused through focus follows mouse.

This catches some windows, but not all of them, because e.g some "Settings/Preferences Dialogs" etc. identify as a "root window". This is where the second part (already implemented in #2036) kicks in; only windows that match the "AXRole" and "AXSubrole" of a "real window" will be tiled, all other types will be treated as floating. All of these windows are eligible targets for window rules, and in this part it might be necessary for the user to step in correct the behaviour for some applications/windows.

Additionally, rules that set manage=on without specifying AXRole and AXSubrole filter, will now only apply to windows that have AXRole=AXWindow and AXSubrole=AXStandardWindow.

The root-window property is also added as an attribute returned in window queries.