Enable MSAA support for all non-web platforms
MSAA support is built into GLES3 core, eliminating the need to check for GL_EXT_framebuffer_multisample, which was necessary only in GLES2 due to the lack of inherent multisample framebuffer support. This commit corrects an oversight from GLES2-based code, ensuring compatibility with GLES3 where multisampling is natively supported without extensions.