[IIQ] Translation support for Question Image Alt-text - #14394

Description

[IIQ]Adding Translation support for Question Image Alt-text.

TDD- https://docs.google.com/document/d/1uG-2TKiFAERGpVRMMcU9OXGyM3hVsOVbR-ta3_rFP1I/edit?tab=t.0

I have diverted a little bit away from the TDD as I found a better design during implementation. I have updated the TDD to contain this section
TDD update 10/30- Instead of creating a separate StaticQuestionTranslationForm, we are extending the existing QuestionTranslationForm to include imageDescription. In CiviForm’s data model, localizedImageDescription lives on the base QuestionDefinition and QuestionModel, rather than being exclusive to a static question subclass. Keeping the field on the base form avoids unnecessary class boilerplate code and the implementation can be easily extended to other question types in future if need be.

Release notes

Adding Translation support for Question Image Alt-text.

Checklist

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General

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• Added the correct label (see docs for more info): < feature | enhancement | bug | under-development | dependencies | infrastructure | ignore-for-release | database >
• Assigned to a specific person, civiform/developers, or a more specific round-robin list
• Added an additional reviewer from civiform/eng-admin as FYI (if this PR includes functionality changes and neither you nor the primary reviewer is an admin)
• Added an additional reviewer as required if changes potentially affect the security of the application.
• Removed the release notes section if the title is sufficient for the release notes description, or put more details in that section.
• Created unit and/or browser tests which fail without the change (if possible)
• Performed manual testing (Chrome and Firefox if it includes front-end changes)
• Extended the README / documentation, if necessary. For user-facing features, consider updating the user docs. For "under-the-hood" changes or things more relevant to developers, consider updating the dev wiki.
• Ensured PII wasn't added to any new logs, unless it was guarded by isDevOrStaging
• Noted in the PR description which, if any, code in this PR was generated by AI.

Instructions for manual testing

1. Login as a CiviForm admin and enable two flags ADMIN_UI_MIGRATION_J2HTML_TO_THYMELEAF_SC_ENABLED and IMAGES_IN_QUESTION_FEATURE_ENABLED
2. Add a static questions and save.
3. Edit the Static question and add an image + alt-text
4. Go to the questions translation screen and see the alt-text ready for translation in the form. Add alt-text description and save in the language.
5. You should see the translated alt-text as an applicant(screen reader only) in the same language.

Issue(s) this completes

Fixes #13863