WebGL2: support TexImage3D (#37718)

Add TexImage3D method to WebGL2RenderingContext

Testing: conformance2 should pass. Also it should get
http://webglsamples.org/WebGL2Samples/#texture_2d_array and
http://webglsamples.org/WebGL2Samples/#texture_3d running.
Fixes: #26511

Now Servo can run texture_2d_array and texture_3d samples!

![圖片](https://github.com/user-attachments/assets/41b87563-08b8-4db3-b503-12f3a61dbed7)

![圖片](https://github.com/user-attachments/assets/3c62a4de-35ea-488d-b2e5-00e3aed52090)

And it can now run three.js too!

![圖片](https://github.com/user-attachments/assets/d880aa92-a154-4895-aa06-b7919d1fc869)

---------

Signed-off-by: Wu Yu Wei <yuweiwu@pm.me>

components/webgl/webgl_thread.rs

@@ -1582,6 +1582,48 @@ impl WebGLImpl {
             WebGLCommand::SetViewport(x, y, width, height) => unsafe {
                 gl.viewport(x, y, width, height)
             },
+            WebGLCommand::TexImage3D {
+                target,
+                level,
+                internal_format,
+                size,
+                depth,
+                format,
+                data_type,
+                effective_data_type,
+                unpacking_alignment,
+                alpha_treatment,
+                y_axis_treatment,
+                pixel_format,
+                ref data,
+            } => {
+                let pixels = prepare_pixels(
+                    internal_format,
+                    data_type,
+                    size,
+                    unpacking_alignment,
+                    alpha_treatment,
+                    y_axis_treatment,
+                    pixel_format,
+                    Cow::Borrowed(data),
+                );
+
+                unsafe {
+                    gl.pixel_store_i32(gl::UNPACK_ALIGNMENT, unpacking_alignment as i32);
+                    gl.tex_image_3d(
+                        target,
+                        level as i32,
+                        internal_format.as_gl_constant() as i32,
+                        size.width as i32,
+                        size.height as i32,
+                        depth as i32,
+                        0,
+                        format.as_gl_constant(),
+                        effective_data_type,
+                        PixelUnpackData::Slice(Some(&pixels)),
+                    );
+                }
+            },
             WebGLCommand::TexImage2D {
                 target,
                 level,