Add missing licenses

[sovrasov]

Summary

ruff configuration looks hacky now, because we have an outdated ruff.
To apply new one, refactoring of the configuration is required.

How to test

Checklist

• I have added unit tests to cover my changes.​
• I have added integration tests to cover my changes.​
• I have ran e2e tests and there is no issues.
• I have added the description of my changes into CHANGELOG in my target branch (e.g., CHANGELOG in develop).​
• I have updated the documentation in my target branch accordingly (e.g., documentation in develop).
• I have linked related issues.

License

• I submit my code changes under the same Apache License that covers the project.
  Feel free to contact the maintainers if that's a concern.
• I have updated the license header for each file (see an example below).

# Copyright (C) 2025 Intel Corporation
# SPDX-License-Identifier: Apache-2.0

[ashwinvaidya17]

Thanks!

[samet-akcay]

Thanks @sovrasov! Now that you added this, maybe we could remove the license section from the pull request template?
https://github.com/openvinotoolkit/training_extensions/blob/develop/.github/pull_request_template.md

[sovrasov]

Thanks @sovrasov! Now that you added this, maybe we could remove the license section from the pull request template? https://github.com/openvinotoolkit/training_extensions/blob/develop/.github/pull_request_template.md

Why should we remove it? The linter doesn't explain how the license should look like, it just checks if the proper header was added.