Shader preemption

[DemiMarie]

Is your feature request related to a problem? Please describe.
GPU resets are often very disruptive. For instance, on AMD GPUs, they often kill the Wayland compositor and thus bring down the entire user login session. On macOS, GPU resets still cause glitches in other applications.

Describe the solution you'd like
Insert preemption polls in generated shaders to ensure that a shader terminates before the driver must kill it. This could also allow long-running compute by saving and restoring shader state.

Describe alternatives you've considered
None.

Additional context
WGPU must ensure that shaders terminate to avoid memory unsafety in generated code.