Style: Harmonize header includes in modules

This applies our existing style guide, and adds a new rule to that style
guide for modular components such as platform ports and modules:

Includes from the platform port or module ("local" includes) should be listed
first in their own block using relative paths, before Godot's "core" includes
which use "absolute" (project folder relative) paths, and finally thirdparty
includes.

Includes in `#ifdef`s come after their relevant section, i.e. the overall
structure is:

- Local includes
  * Conditional local includes
- Core includes
  * Conditional core includes
- Thirdparty includes
  * Conditional thirdparty includes

3 files changed, 6 insertions, 4 deletions

diff --git a/modules/webxr/godot_webxr.h b/modules/webxr/godot_webxr.h
index 554ca0398b..a7ce7e45d2 100644
--- a/modules/webxr/godot_webxr.h
+++ b/modules/webxr/godot_webxr.h
@@ -35,7 +35,7 @@
 extern "C" {
 #endif
 
-#include "stddef.h"
+#include <stddef.h>
 
 enum WebXRInputEvent {
 	WEBXR_INPUT_EVENT_SELECTSTART,
diff --git a/modules/webxr/webxr_interface.cpp b/modules/webxr/webxr_interface.cpp
index 5e30d0c996..85ed9f472e 100644
--- a/modules/webxr/webxr_interface.cpp
+++ b/modules/webxr/webxr_interface.cpp
@@ -29,6 +29,7 @@
 /**************************************************************************/
 
 #include "webxr_interface.h"
+
 #include <stdlib.h>
 
 void WebXRInterface::_bind_methods() {
diff --git a/modules/webxr/webxr_interface_js.cpp b/modules/webxr/webxr_interface_js.cpp
index e1df2ea94e..47f20ce1a3 100644
--- a/modules/webxr/webxr_interface_js.cpp
+++ b/modules/webxr/webxr_interface_js.cpp
@@ -28,20 +28,21 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
+#include "webxr_interface_js.h"
+
 #ifdef WEB_ENABLED
 
-#include "webxr_interface_js.h"
+#include "godot_webxr.h"
 
 #include "core/input/input.h"
 #include "core/os/os.h"
 #include "drivers/gles3/storage/texture_storage.h"
-#include "emscripten.h"
-#include "godot_webxr.h"
 #include "scene/main/scene_tree.h"
 #include "scene/main/window.h"
 #include "servers/rendering/renderer_compositor.h"
 #include "servers/rendering/rendering_server_globals.h"
 
+#include <emscripten.h>
 #include <stdlib.h>
 
 void _emwebxr_on_session_supported(char *p_session_mode, int p_supported) {