Add single-file Vulkan pipeline cache save/load support with strict device, driver, shader, and payload validation. Cache compiled SPIR-V per shader hash alongside the driver pipeline cache blob, add focused cache tests, and document the current Vulkan pipeline cache architecture and usage.
Limit Vulkan layer test cache growth with a shared test-only pipeline cache window so repeated test_layer() calls can still exercise cache reuse.
Co-authored-by: futz12 <56149058+futz12@users.noreply.github.com>
Co-authored-by: CLV-Iclucia <89170890+CLV-Iclucia@users.noreply.github.com>
nihui