OpenXR: VR Advanced Locomotion Phase 1

Includes the following changes to the existing Locomotion system for VR Scene Inspection:
 * new VR Navigation Preferences and VR Session Settings
 * changes to XR raycast logic and its visualization
 * new XR vignette that appears when moving
 * snap turning

Pull Request: https://projects.blender.org/blender/blender/pulls/144241

release/datafiles/userdef/userdef_default.c

@@ -208,6 +208,14 @@ const UserDef U_default = {
             .flag = 0,
         },
 
+    .xr_navigation =
+        {
+            .vignette_intensity = 60.0f,
+            .turn_amount = DEG2RAD(30),
+            .turn_speed = DEG2RAD(60),
+            .flag = USER_XR_NAV_SNAP_TURN,
+        },
+
     .space_data =
         {
             .section_active = USER_SECTION_INTERFACE,
@@ -246,4 +254,12 @@ const UserDef U_default = {
         {
             .is_dirty = 0,
         },
+
+    .xr_navigation = 
+        {
+            .vignette_intensity = 60.0f,
+            .turn_amount = DEG2RAD(30),
+            .turn_speed = DEG2RAD(60),
+            .flag = USER_XR_NAV_SNAP_TURN,
+        },
 };