refactor(configgen): evmapy controller monitor and hotkeygen mouse reset

[bryanforbes]

Move controller monitoring logic from emulatorlauncher.py into evmapy module as a _ControllerMonitor dataclass, encapsulating thread management, SDL2/pyudev usage, and controller state tracking. The evmapy context manager now returns self and exposes start_monitoring_controllers() for deferred thread startup.

Convert hotkeygen's set_hotkeygen_context() generator function into a HotkeygenManager dataclass-based context manager, and move the mouse reset logic into it as reset_mouse().

Remove global mutable state (_active_player_controllers, _evmapy_instance, _player_controllers_lock) and the standalone _controller_monitor_thread/_reconfigure_evmapy_on_the_fly functions from emulatorlauncher.py.

[dmanlfc]

@nadenislamarre looks ok but @bryanforbes needs to rebase it

[nadenislamarre]

hard to tell with the quantity of code.
globally seems ok.
but bryanforbes is a trusted person, it is ok for me.

[nadenislamarre]

and the target is legit : reorganize configgen for which many features were added over the time.