Add support for ARB_gpu_shader_fp64

Add support for ARB_gpu_shader_fp64

GLSL Version : >= 150

Purpose:
Allow users to use features by enabling this extension, even in low versions.

Extension Name:
ARB_gpu_shader_fp64

Builtin-variables:
Nah

Builtin-functions:
functions overloaded for this extension, please check registry in reference.

Keywords:
Double

Features:
add support for type "double"

Reference:
https://www.khronos.org/registry/OpenGL/extensions/ARB/ARB_gpu_shader_fp64.txt

Add support for implicit conversion

1. Remove builtin double vertex (this is introduced by vertex_attrib_64bit
2. Add extension check and implicit conversion as double has been introduced
3. Add test results.