[naga glsl-out] Implement coordinate clamping for textureSampleBaseClampToEdge for GLSL

[jamienicol]

#7709 is implementing textureSampleBaseClampToEdge() for texture_2d<f32> textures for MSL, HLSL, and SPIRV backends. On GLSL shaders using this will compile and run, but the coordinates won't be clamped as per the spec. This issue tracks finishing the GLSL implementation