Allow more WebGL2 FBO attachment formats
Add support for most of the framebuffer attachment formats introduced in WebGL2 for textures and renderbuffers. Related format tables: - https://www.khronos.org/registry/OpenGL-Refpages/es3.0/html/glTexImage2D.xhtml - https://www.khronos.org/registry/OpenGL-Refpages/es3.0/html/glRenderbufferStorage.xhtml