Add 7 new difftests and push constants support

[LegNeato]

I wanted to increase coverage, so I worked with AI to bang out some tests and infra changes.

New tests:

• bitwise_ops: bit manipulation operations
• trig_ops: trigonometric functions
• control_flow_complex: nested loops and complex control flow
• vector_swizzle: vector component access and swizzling
• memory_barriers: workgroup memory synchronization
• vector_extract_insert: dynamic vector element access
• push_constants: push constants in compute shaders

Infrastructure changes:

• Add WgpuComputeTestPushConstants for push constant support
• Enable PUSH_CONSTANTS feature in wgpu when needed

[Firestar99]

I'd love to have these for testing my const folding in #317

[Firestar99]

CI Ubuntu reports these failures:
difftests::lang::core::ops::math_ops
difftests::lang::core::ops::matrix_ops
difftests::lang::core::ops::vector_ops

On my machine I get these failures:
difftests::lang::core::ops::math_ops
difftests::lang::core::ops::matrix_ops

Could this be float inaccuracies between vendors?

[LegNeato]

Yeah, I think it is floats because they all passed locally after I took care of some existing float issues. I'll take a look and either round or omit.

[LegNeato]

I added a compat_round! macro that handled most of the differences, but could not get all of them. So I added epsilon support when comparing. And then because I was debugging with python scripts I added better debug output when dealing with f32s. And because I did that I reworked all the output cases to match.

This is a lot of code and I don't really expect you to review it...AI wrote a lot of it and I reviewed and tweaked. I figure we'll iterate on main as it is super self-contained. I can probably break it up if you want though!

As an aside, I think some of these should be runtests, as I am not sure what value we get diffing with glsl for all of them. BTW, if test times get long we can shard in CI as theoretically we could have 1 job for each test as they are unrelated.

[LegNeato]

(note it is not set to automerge as I'll want to squash first)

[LegNeato]

Ok, the windows issue is definitely a wgpu + naga (dxc) bug.

[LegNeato]

I've pulled out the repo for the wgpu/naga bug: https://github.com/LegNeato/wgpu-workgroup-memory-bug