translation: translation of observer pattern to Italian

[leonardol]

Translation of the 'Observer' pattern README.md into Italian

This pull request adds the Italian translation of the README.md for the 'Observer' design pattern, which explains the pattern itself.

This pull request is related to issue #2314

Changes made in this pull request:

• Created a new README.md file in Italian with the translation of the English README.md.
• Placed the new README.md file in the 'localization/it/observer' directory.
• Ensured that the translation accurately conveys the content and meaning of the original document.
• Maintained the same format, style and layout of the English README.md.
• Checked for grammar and spelling errors in the translation.
• Provided the link diagram of the class structure in the Italian README.md, ensuring it aligns with the content of the original README.md.
• This contribution aims to make the project more accessible to Italian-speaking developers and users. It follows the guidelines provided in the project's contributing instructions.

For detailed contributing instructions see https://github.com/iluwatar/java-design-patterns/wiki/01.-How-to-contribute

I look forward to your feedback and any necessary revisions to improve the quality of the Italian translation.

Allow edits by maintainers
Remember, contributions to this repository should follow its contributing guidelines.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

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[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[stale]

Closed due to inactivity. Thank you for your contributions.

[iluwatar]

Looks good! Thank you for the contribution 🎉

@all-contributors please add @leonardol for translation

[allcontributors]

@iluwatar

I couldn't determine any contributions to add, did you specify any contributions?
Please make sure to use valid contribution names.

@leonardol already contributed before to translation

[sonarqubecloud]

Quality Gate failed

Failed conditions
C Reliability Rating on New Code (required ≥ A)
C Maintainability Rating on New Code (required ≥ A)

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