fix(metal): Don't panic on OOM in create_buffer (gfx-rs#8994)

Author: andyleiserson

cts_runner/test.lst

@@ -56,6 +56,7 @@ webgpu:api,operation,vertex_state,correctness:setVertexBuffer_offset_and_attribu
 webgpu:api,validation,buffer,create:*
 webgpu:api,validation,buffer,destroy:*
 webgpu:api,validation,capability_checks,limits,maxBindGroups:setBindGroup,*
+webgpu:api,validation,capability_checks,limits,maxBufferSize:*
 //FAIL: other `maxInterStageShaderVariables` cases w/ limitTest ∈ [underDefault, overMaximum]
 // https://github.com/gfx-rs/wgpu/issues/8945
 webgpu:api,validation,capability_checks,limits,maxInterStageShaderVariables:createRenderPipeline,at_over:limitTest="atDefault";*

wgpu-hal/src/metal/device.rs

@@ -418,7 +418,7 @@ impl crate::Device for super::Device {
                 .shared
                 .device
                 .newBufferWithLength_options(desc.size as usize, options)
-                .unwrap();
+                .ok_or(crate::DeviceError::OutOfMemory)?;
             if let Some(label) = desc.label {
                 raw.setLabel(Some(&NSString::from_str(label)));
             }