[Port dspace-9_x] Fix accessibility issues with placeholder text in submission forms by removing placeholders

[FrancescoMolinaro]

References

Fixes #4198
Manual backport of #4199

Description

Following what is described in https://www.deque.com/blog/accessible-forms-the-problem-with-placeholders/ as an issue with placeholder, this PR removes all placeholders on submission form fields (replacing them with labels where needed)

Instructions for Reviewers

Placeholders should no longer exist on any fields within the submission form. The Series/Report No. field now has sublabels.

Checklist

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However, reviewers may request that you complete any actions in this list if you have not done so. If you are unsure about an item in the checklist, don't hesitate to ask. We're here to help!

• My PR is created against the main branch of code (unless it is a backport or is fixing an issue specific to an older branch).
• My PR is small in size (e.g. less than 1,000 lines of code, not including comments & specs/tests), or I have provided reasons as to why that's not possible.
• My PR passes ESLint validation using npm run lint
• My PR doesn't introduce circular dependencies (verified via npm run check-circ-deps)
• My PR includes TypeDoc comments for all new (or modified) public methods and classes. It also includes TypeDoc for large or complex private methods.
• My PR passes all specs/tests and includes new/updated specs or tests based on the Code Testing Guide.
• My PR aligns with Accessibility guidelines if it makes changes to the user interface.
• My PR uses i18n (internationalization) keys instead of hardcoded English text, to allow for translations.
• My PR includes details on how to test it. I've provided clear instructions to reviewers on how to successfully test this fix or feature.
• If my PR includes new libraries/dependencies (in package.json), I've made sure their licenses align with the DSpace BSD License based on the Licensing of Contributions documentation.
• If my PR includes new features or configurations, I've provided basic technical documentation in the PR itself.
• If my PR fixes an issue ticket, I've linked them together.

[tdonohue]

@FrancescoMolinaro : I gave this a review today, comparing it to #4199. However, I think there's a small change that is missing in this backport. Please see my inline comment below.

[FrancescoMolinaro]

Hi @tdonohue, thanks for the catch, I have added the missing change, should be ok now.

[tdonohue]

👍 Thanks @FrancescoMolinaro ! This looks correct to me now.