fix pil import in VLM

[eaidova]

What does this PR do?

make PIL optional for running optimum-intel. This dependency is not listed in requirements and used only for type checking, for avoid inconvenience for nlp part only users, it is better make its import optional. For cases, where it is really used, it should be already installed and checked by source libraries like transformers and diffusers

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you make sure to update the documentation with your changes?
• Did you write any new necessary tests?

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[nikita-savelyevv]

I've examined a dependency tree after pip install .[openvino] and see that Pillow gets installed. It is a dependency of nncf, which in turn is installed under [openvino] option. Please see the tree below.

I'm curious, which scenario have you considered for this fix?

nncf==2.14.0
  jsonschema==4.23.0
    attrs==24.2.0
    jsonschema-specifications==2024.10.1
      referencing==0.35.1
        attrs==24.2.0
        rpds-py==0.21.0
    referencing==0.35.1
      attrs==24.2.0
      rpds-py==0.21.0
    rpds-py==0.21.0
  jstyleson==0.0.2
  natsort==8.4.0
  networkx==3.2.1
  ninja==1.11.1.1
  numpy==2.0.2
  openvino-telemetry==2024.5.0
  packaging==24.2
  pandas==2.2.3
    numpy==2.0.2
    python-dateutil==2.9.0.post0
      six==1.16.0
    pytz==2024.2
    tzdata==2024.2
  psutil==6.1.0
  pydot==2.0.0
    pyparsing==3.2.0
  pymoo==0.6.1.3
    alive-progress==3.2.0
      about-time==4.2.1
      grapheme==0.6.0
    autograd==1.7.0
      numpy==2.0.2
    cma==3.2.2
      numpy==2.0.2
    Deprecated==1.2.15
      wrapt==1.17.0
    dill==0.3.8
    matplotlib==3.9.2
      contourpy==1.3.0
        numpy==2.0.2
      cycler==0.12.1
      fonttools==4.55.0
      importlib_resources==6.4.5
        zipp==3.21.0
      kiwisolver==1.4.7
      numpy==2.0.2
      packaging==24.2
      pillow==11.0.0

[eaidova]

on my end it failed in openvino notebooks, where optimum-intel and ov/nncv was installed separately without usage extra