The extension directives must occur before any non-preprocessor tokens.

Hi,
the ogl specs says : **the extension directives must occur before any non-preprocessor tokens.** . So follow the spec,
the glslang should report the error for following shader:

```
#version 300 es
#extension all : warn

precision mediump float;
in highp vec4 dEQP_Position;

void main()
{
#extension all : disable // compile error
gl_Position = vec4(1.0);
}
```

spec:
https://www.khronos.org/registry/OpenGL/specs/gl/GLSLangSpec.4.60.pdf

Start by reproducing the shader in the issue with glslang and read the GLSL extension-directive parsing and validation entry points. Confirm that a directive after non-preprocessor tokens is diagnosed as an error, then add or update a regression test showing the expected diagnostic.

Written by the indexing model from the issue text.