Cleanup: Remove unused parameter

Cleanup: Improve description for XR absolute tracking

XR: Only show ref space warnings in debug-xr mode

This avoids spamming the console for users who have not set up a
tracking space/boundary for their headsets.

XR: Fix potential crash when toggling session

XR: Versioning for session draw flags, base scale

XR: View adjustments for variable viewer scale

This adjusts some calculations and visibility flags for XR viewports in
order to account for a possible scale factor in the XR view matrix.

This scale factor can be introduced via the XR session settings base
scale, which allows a viewer to begin their session at a specific
reference scale, or the XR session state navigation scale, which allows
a viewer to adjust their scale relative to the reference scale during
the session.

Reviewed by Severin as part of D11501, but requested to be committed
separately.

XR Controller Support Step 5: Navigation

Adds navigation transforms (pose, scale) to the XR session state that
will be applied to the viewer/controller poses. By manipulating these
values, a viewer can move through the VR viewport without the need to
physically walk through it.

Add-ons can access these transforms via Python
(XrSessionState.navigation_location/rotation/scale) to use with custom
operators.

Also adds 3 new VR navigation operators that will be exposed to users
as default actions in the VR Scene Inspection add-on. While all three
of these operators have custom properties that can greatly influence
their behaviors, for now these properties will not be accessible by
users from the UI. However, other add-ons can still set these custom
properties if they desire.

1). Raycast-based teleport
Moves the user to a location pointed at on a mesh object. The result
can optionally be constrained to specific axes, for example to achieve
"elevation snapping" behavior by constraining to the Z-axis. In
addition, one can specify an interpolation factor and offset.

Credit to KISKA for the elevation snapping concept.

2). "Grab" navigation
Moves the user through the viewport by pressing inputs on one or two
held controllers and applying deltas to the navigation matrix based on
the displacement of these controllers. When inputs on both controllers
are pressed at the same time (bimanual interaction), the user can scale
themselves relative to the scene based on the distance between the
controllers.

Also supports locks for location, rotation, and scale.

3). Fly navigation
Navigates the viewport by pressing a button and moving/turning relative to
navigation space or the VR viewer or controller. Via the operator's
properties, one can select from a variety of these modes as well as
specify the min/max speed and whether to lock elevation.

Reviewed By: Severin

Differential Revision: https://developer.blender.org/D11501

Extern: Add modifications diff for TinyGLTF

This should have been added in ee49991999c9.

Fix build error due to conflicting types

XR Controller Support Step 4: Controller Drawing

Addresses T77127 (Controller Drawing).

Adds VR controller visualization and custom drawing via draw
handlers. Add-ons can draw to the XR surface (headset display) and
mirror window by adding a View3D draw handler of region type 'XR' and
draw type 'POST_VIEW'. Controller drawing and custom overlays can be
toggled individually as XR session options, which will be added in a
future update to the VR Scene Inspection add-on.

For the actual drawing, the OpenXR XR_MSFT_controller_model extension
is used to load a glTF model provided by the XR runtime. The model's
vertex data is then used to create a GPUBatch in the XR session
state. Finally, this batch is drawn via the XR surface draw handler
mentioned above.

For runtimes that do not support the controller model extension, a
a simple fallback shape (sphere) is drawn instead.

Reviewed By: Severin, fclem

Differential Revision: https://developer.blender.org/D10948