OV nf4 support (#3209)

### Changes

- Added `nf4` precision for OV `GraphConverter`.

### Reason for changes

- `nf4` precision support.

### Related tickets

- 153357

### Tests

- Added

nncf/openvino/graph/nncf_graph_builder.py

@@ -48,6 +48,7 @@ def convert_to_nncf_dtype(ov_type: ov.Type) -> Dtype:
             "bf16": "float",
             "f32": "float",
             "f64": "float",
+            "nf4": "float",
             "i4": "int",
             "i8": "int",
             "i16": "int",

tests/openvino/native/data/2024.6/reference_graphs/original_nncf_graph/nf4_FPModel.dot

@@ -0,0 +1,17 @@
+strict digraph  {
+"0 Input" [id=0, type=Parameter];
+"1 MatMul" [id=1, type=MatMul];
+"2 Add" [id=2, type=Add];
+"3 Result_Add" [id=3, type=Result];
+"4 Convert_6" [id=4, type=Convert];
+"5 MatMul_bias" [id=5, type=Constant];
+"6 Convert_3" [id=6, type=Convert];
+"7 MatMul_const" [id=7, type=Constant];
+"0 Input" -> "1 MatMul"  [label="[1, 3, 4, 2]", style=solid];
+"1 MatMul" -> "2 Add"  [label="[1, 3, 2, 5]", style=solid];
+"2 Add" -> "3 Result_Add"  [label="[1, 3, 2, 5]", style=solid];
+"4 Convert_6" -> "2 Add"  [label="[1, 3, 1, 1]", style=solid];
+"5 MatMul_bias" -> "4 Convert_6"  [label="[1, 3, 1, 1]", style=solid];
+"6 Convert_3" -> "1 MatMul"  [label="[1, 3, 4, 5]", style=solid];
+"7 MatMul_const" -> "6 Convert_3"  [label="[1, 3, 4, 5]", style=solid];
+}

tests/openvino/native/test_nncf_graph_builder.py

@@ -21,6 +21,7 @@
 from tests.openvino.native.common import convert_torch_model
 from tests.openvino.native.common import get_actual_reference_for_current_openvino
 from tests.openvino.native.models import SYNTHETIC_MODELS
+from tests.openvino.native.models import FPModel
 from tests.openvino.native.models import ParallelEdgesModel
 from tests.openvino.native.models import get_torch_model_info
 
@@ -34,6 +35,19 @@ def test_compare_nncf_graph_synthetic_models(model_cls_to_test):
     compare_nncf_graphs(model_to_test.ov_model, path_to_dot)
 
 
+@pytest.mark.parametrize(
+    "model,precision",
+    [
+        (FPModel(const_dtype=ov.Type.nf4), "nf4"),
+    ],
+)
+def test_compare_nncf_graph_precision_synthetic_models(model, precision):
+    path_to_dot = get_actual_reference_for_current_openvino(
+        REFERENCE_GRAPHS_DIR / f"{precision}_{model.ref_graph_name}"
+    )
+    compare_nncf_graphs(model.ov_model, path_to_dot)
+
+
 @pytest.mark.parametrize(
     "model_name",
     (
@@ -101,6 +115,7 @@ def _get_default_nncf_graph_edge(from_node, to_node, input_port_id, output_port_
         (ov.Type.f16, Dtype.FLOAT),
         (ov.Type.f32, Dtype.FLOAT),
         (ov.Type.f64, Dtype.FLOAT),
+        (ov.Type.nf4, Dtype.FLOAT),
         (ov.Type.i4, Dtype.INTEGER),
         (ov.Type.i8, Dtype.INTEGER),
         (ov.Type.i16, Dtype.INTEGER),
@@ -124,7 +139,6 @@ def test_convert_to_nncf_dtype_supported_types(ov_type: ov.Type, expected_nncf_d
 @pytest.mark.parametrize(
     "ov_type",
     [
-        ov.Type.nf4,
         ov.Type.undefined,
         ov.Type.f8e4m3,
         ov.Type.f8e5m2,