Update bgfx.cmake to restored merge-based bgfx master (#1639)

Updates the bgfx.cmake FetchContent reference to point to the restored
merge-based bgfx history instead of the rebased version.

### Changes
- **bgfx.cmake**: `1b10ed5` → `353465d` (updated bgfx submodule to new
merge-based master)
- **bgfx**: `3b38e72` (rebased) → `2033529` (merge commit restoring
original history + upstream at b12126336)

The file contents are identical — only the git history structure changes
(merge-based instead of rebased).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bghgary

CMakeLists.txt

@@ -35,7 +35,7 @@ FetchContent_Declare(base-n
     EXCLUDE_FROM_ALL)
 FetchContent_Declare(bgfx.cmake
     GIT_REPOSITORY https://github.com/BabylonJS/bgfx.cmake.git
-    GIT_TAG 1b10ed55fadc0171c736f9638514ae715a1d97de
+    GIT_TAG 353465dbc9fc9cfd9d4593f74f0107e87776ddc7
     EXCLUDE_FROM_ALL)
 FetchContent_Declare(CMakeExtensions
     GIT_REPOSITORY https://github.com/BabylonJS/CMakeExtensions.git