Add item throwing mechanics to VR configuration and input handling

- Introduced `vrCockpitItemThrow` configuration option to enable throwing items in VR.
- Implemented `ThrowDetector` and `ThrowSequence` classes to manage item throwing mechanics based on hand movements.
- Updated `OpenXRInput` to handle item throwing based on hand swings, integrating with existing VR input systems.
- Enhanced settings overlay to allow users to toggle item throwing functionality.
- Added tests for item throwing mechanics, ensuring correct behavior for various hand movements and conditions.

runtime/include/vr/openxr_input.h

@@ -7,6 +7,7 @@
 #include "vr/camera_toggle.h"
 #include "vr/openxr_driving.h"
 #include "vr/openxr_hand_tracking.h"
+#include "vr/openxr_item_throw.h"
 #include "vr/openxr_runtime.h"
 #include "vr/openxr_settings_panel.h"
 #include "vr/openxr_wii_remote.h"
@@ -72,6 +73,11 @@ struct OpenXRPointerScreen {
 // the game (a shoulder on the gamepad; as a Wii Remote the grips are unbound,
 // so a hand on the wheel cannot hold down a button).
 //
+// Throwing the held item ([vr] cockpit_item_throw, openxr_item_throw.h): in the
+// cockpit, a quick swing forward or back of the hand showing the item pushes the
+// left stick that way while the left trigger (Z, or the GameCube's L) is pressed
+// and released, which the game reads as an aimed throw.
+//
 // Tracked hands ([vr] hand_tracking, with hand steering): two hand trackers
 // (XR_EXT_hand_tracking) located every frame give the cockpit the hands' own
 // joints, from the controllers' touch sensors while they are held and from the
@@ -160,6 +166,9 @@ private:
     void UpdateDriving(XrTime display_time, const driving::SeatFrame& seat,
                        std::array<wii_remote::HandInputs, kHands>& hands, bool withheld);
     void ResetDriving();
+    // After the wheel and the bare hands: the item hand's swing, and the throw it
+    // plays on the left hand's stick and trigger.
+    void UpdateItemThrow(float dt_seconds, std::array<wii_remote::HandInputs, kHands>& hands, bool withheld);
     // Tracked hands: the extension's functions at Create, the trackers as the
     // settings ask for them, and both hands located for `time`, their joints
     // in `seat` when it is valid.
@@ -255,6 +264,10 @@ private:
     hand_tracking::FlickDetector m_flick;
     XrTime m_flick_start = 0;
     bool m_injected_flick_held = false;
+    // Throwing the held item.
+    item_throw::ThrowDetector m_throw;
+    item_throw::ThrowSequence m_throw_sequence;
+    bool m_injected_throw_held = false;
     uint64_t m_profile_serial = 0;
 
     bool m_created = false;