Avoid import matplotlib (#3720)

### Changes

Import matplotlib inside function and under
`skip_if_dependency_unavailable` decorator

### Reason for changes

`matplotlib` is not main NNCF requirements, it's part of optional
dependencies `nncf[plots]`
Currently matplotlib installing with `pymoo` but it will be removed in
the next release.

Author: AlexanderDokuchaev

src/nncf/quantization/algorithms/weight_compression/lora_correction.py

@@ -11,13 +11,13 @@
 from pathlib import Path
 from typing import Optional
 
-import matplotlib.pyplot as plt
 import pandas as pd
 
 import nncf
 from nncf.common.logging import nncf_logger
 from nncf.common.utils.debug import DEBUG_LOG_DIR
 from nncf.common.utils.debug import is_debug
+from nncf.common.utils.decorators import skip_if_dependency_unavailable
 from nncf.experimental.common.tensor_statistics.statistics import WCTensorStatistic
 from nncf.parameters import CompressWeightsMode
 from nncf.quantization.advanced_parameters import AdvancedLoraCorrectionParameters
@@ -43,7 +43,10 @@ def __init__(self):
     def add_noises(self, layer_name: str, value: float):
         self._noise_per_layer[layer_name] = value
 
+    @skip_if_dependency_unavailable(dependencies=["matplotlib.pyplot"])
     def dump_data(self):
+        import matplotlib.pyplot as plt
+
         if not self._noise_per_layer:
             return
         dump_dir = Path(DEBUG_LOG_DIR) / "lora"