Added Wgsl keywords and identifiers

[Zelif]

Adding WGSL highlighting support:
#25
WGSL Spec

This still needs work, I haven't touched the regex's below (taken from the GLSL section, feel free to remove the comments; I had added them to keep track of what I was adding.

What PaletteIndex would attributes fall under? (ive added it to keywords for now)

@vertex
fn vertex_main_function(@builtin(position) coord: vec4<f32>) {
    // ....
}

[Zelif]

Unsure how to handle the <TYPE>
Updated most of the regex's that were inside the WGSL spec (unsure if they are any good)
There are duplicates in keywords and identifiers, unsure what ones to put them in.
I am sure this can be improved by A LOT, but hopefully is a start.
Ended up with:

[santaclose]

thank you for the PR. Can you squash the commits?