Accessibility on the Edit metadata tab

[Andrea-Guevara]

References

• Fixes #1193

Description

Addition of the "aria-label" attribute to the add, save, discard and undo buttons on the metadata editing page to ensure that they are "visible" to screen readers, even when the CSS is completely disabled.

Instructions for reviewers

List of changes in this PR:

• The html of the dso-edit-metadata component has been changed.
• The "aria-label" attribute has been added to all the buttons in the component.
• The translation key used in the "title" of each button has been used for "[attr.aria-label]".

To reproduce:

• Log in to dspace as an administrator.
• Go to an item and click on the edit button.
• Go to the "Metadata" section.
• Check the page with an accessibility tool.