WAsm implementation of PReLU microkernels

Up to 50% speedup on WAsm under ARM64

PiperOrigin-RevId: 318336401
diff --git a/test/f32-prelu.yaml b/test/f32-prelu.yaml
index 2c6309b..cd87736 100644
--- a/test/f32-prelu.yaml
+++ b/test/f32-prelu.yaml
@@ -20,5 +20,7 @@
 - name: xnn_f32_prelu_ukernel__wasmsimd_bitselect_2x8
 - name: xnn_f32_prelu_ukernel__wasmsimd_minmax_2x4
 - name: xnn_f32_prelu_ukernel__wasmsimd_minmax_2x8
+- name: xnn_f32_prelu_ukernel__wasm_2x1
+- name: xnn_f32_prelu_ukernel__wasm_2x4
 - name: xnn_f32_prelu_ukernel__scalar_2x1
 - name: xnn_f32_prelu_ukernel__scalar_2x4