fix(content): Coilgun fixes

[yay855]

Purpose of change

The coilgun previously could not autofire like the nail rifle, nor did it look like a rifle. Its native sprite made it look like a small pistol when wielded and some sci-fi space gun when on the ground. Furthermore, the nail rifle counted as both a pistol and a rifle thanks to an extend line.

Describe the solution

The coilgun now can autofire like the nail rifle, it has the sprite of the H&K G80 railgun now, and the nail rifle now counts as a rifle instead of a pistol.

Describe alternatives you've considered

Testing

Additional context

Checklist

[chaosvolt]

I cri