[Proposal] std.isKnownAtComptime

[iwoplaza]

This function would return true if the passed-in value is known at comptime.

• When called in JS, it would always return true
• When called during codegen, it would return true if the passed in snippet is known at comptime.

As an example, this can be useful to conditionally apply unrolling depending on if the iterable's length is known at comptime.

for (const boid of std.isKnownAtComptime(boids.$.length) ? tgpu.unroll(boids.$) : boids.$) {
  // ...
}