AtomicFunctionNode: Fix return types

[thelazylamaGit]

When working with atomic nodes such as

const count = float(atomicLoad(trailCounts.element(idx)))

typescript would complain because AtomicFunctionNode wasn't typed <'uint'> properly

No overload matches this call.
Overload 1 of 2, '(value?: number | undefined): VarNode<"float", ConstNode<"float", number>>', gave the following error. Argument of type 'AtomicFunctionNode' is not assignable to parameter of type 'number'.

this PR fixes the issue having it return

atomicLoad<"uint">(pointerNode: Node<"uint">): AtomicFunctionNode<"uint">

instead of

atomicLoad(pointerNode: Node): AtomicFunctionNode

[Methuselah96]

Thanks!