Add a16w8 per-op test for split

Summary:
Add int16 activation / int8 weight (a16w8) quantization tests for `aten.split` on Ethos-U55 and Ethos-U85.

## Changes
- Add `a16w8_split_test_parameters` dict with 3 test configurations covering 1D, 2D, and 3D splits along different axes
- Add `test_split_a16w8_u55_INT` using `EthosU55PipelineINT` with `a16w8_quantization=True, symmetric_io_quantization=True, qtol=128, epsilon=2**-16`
- Add `test_split_a16w8_u85_INT` using `EthosU85PipelineINT` with same kwargs
- Register `ops/test_split.py` in `fbcode/` and `xplat/` `targets.bzl`

bypass-pytorch-oss-checks

Differential Revision: D104533281

Author: christine-long-meta

backends/arm/test/ops/test_split.py

@@ -310,3 +310,42 @@ def test_split_tensor_vgf_quant(test_data: Tuple):
         quantize=True,
     )
     pipeline.run()
+
+
+a16w8_split_test_parameters = {
+    "a16w8_1d_split_2": lambda: (torch.rand(10), 2, 0),
+    "a16w8_2d_split_4": lambda: (torch.rand(8, 4), 4, 0),
+    "a16w8_3d_split_4": lambda: (torch.rand(4, 4, 8), 4, 2),
+}
+
+
+@common.parametrize("test_data", a16w8_split_test_parameters)
+@common.XfailIfNoCorstone300
+def test_split_a16w8_u55_INT(test_data: input_t1):
+    pipeline = EthosU55PipelineINT[input_t1](
+        Split(),
+        test_data(),
+        aten_ops=[],
+        exir_ops=exir_op,
+        a16w8_quantization=True,
+        symmetric_io_quantization=True,
+        qtol=1,
+        epsilon=2**-16,
+    )
+    pipeline.run()
+
+
+@common.parametrize("test_data", a16w8_split_test_parameters)
+@common.XfailIfNoCorstone320
+def test_split_a16w8_u85_INT(test_data: input_t1):
+    pipeline = EthosU85PipelineINT[input_t1](
+        Split(),
+        test_data(),
+        aten_ops=[],
+        exir_ops=exir_op,
+        a16w8_quantization=True,
+        symmetric_io_quantization=True,
+        qtol=1,
+        epsilon=2**-16,
+    )
+    pipeline.run()

backends/arm/test/targets.bzl

@@ -43,6 +43,7 @@ def define_arm_tests():
         "ops/test_conv1d.py",
         "ops/test_gelu.py",
         "ops/test_bmm.py",
+        "ops/test_split.py",
     ]
 
     # Quantization