🔨Refactor methods across files

📝 Description

Move all validations to _validate.py
Move other functions to utils
Create separate dataclass file

✨ Changes

Select what type of change your PR is:

[ ] 🐞 Bug fix (non-breaking change which fixes an issue)
[x] 🔨 Refactor (non-breaking change which refactors the code base)
[ ] 🚀 New feature (non-breaking change which adds functionality)
[ ] 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
[ ] 📚 Documentation update
[ ] 🔒 Security update

✅ Checklist

Before you submit your pull request, please make sure you have completed the following steps:

[ ] 📋 I have summarized my changes in the CHANGELOG and followed the guidelines for my type of change (skip for minor changes, documentation updates, and test enhancements).
[ ] 📚 I have made the necessary updates to the documentation (if applicable).
[ ] 🧪 I have written tests that support my changes and prove that my fix is effective or my feature works (if applicable).

For more information about code review checklists, see the Code Review Checklist.

Codecov Report

Attention: Patch coverage is 74.51737% with 66 lines in your changes missing coverage. Please review.

Please upload report for BASE (feature/pimo@4e117cf). Learn more about missing BASE report.

Files with missing lines	Patch %	Lines
src/anomalib/metrics/per_image/_validate.py	69.62%	41 Missing :warning:
src/anomalib/metrics/per_image/dataclasses.py	72.28%	23 Missing :warning:
src/anomalib/metrics/per_image/binclf_curve.py	85.71%	1 Missing :warning:
src/anomalib/metrics/per_image/pimo.py	90.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## feature/pimo #2321 +/- ## =============================================== Coverage ? 80.68% =============================================== Files ? 255 Lines ? 11695 Branches ? 0 =============================================== Hits ? 9436 Misses ? 2259 Partials ? 0 ``` | [Flag](https://app.codecov.io/gh/openvinotoolkit/anomalib/pull/2321/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openvinotoolkit) | Coverage Δ | | |---|---|---| | [](https://app.codecov.io/gh/openvinotoolkit/anomalib/pull/2321/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openvinotoolkit) | `80.68% <74.51%> (?)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=openvinotoolkit#carryforward-flags-in-the-pull-request-comment) to find out more.

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openvinotoolkit / anomalib