This commit adds the `glFramebufferTextureMultisampleMultiviewOVR`
function, enabling MSAA to work in conjunction with the multiview
extension.
The function's declaration is present in the latest main branch of the
Khronos GLES2 API headers. While directly pulling these updated headers
is the ideal approach, it would necessitate a significant reorganization
of Filament's current header file structure and incorporate more files
than currently needed.
To minimize immediate changes and limit scope, this change adopts
only the necessary function declaration by copying it directly.
BUGS=[417311684]
1e77947758