Add configurable option to show/hide metadatafield names in external import preview

[MMilosz]

Is your feature request related to a problem? Please describe.

When importing items from external sources, the preview modal shows metadata values but it's not always clear which metadata field (e.g., dc.title, dc.contributor.author) corresponds to each value.

This can be confusing for users who need to understand the source mapping (with no access to backend's *-integration.xml files) or for administrators debugging import configurations.

Describe the solution you'd like

Add a configurable option to control the visibility of metadatafield names in the external import preview modal.

My suggestion is to support up to four view modes:

• disable – show only labels (current behavior)
• tooltip – show an info icon with the field name as tooltip (new default)
• labeled – show the field name in parentheses next to the label
• full – show both parentheses label and info icon with tooltip (to be determined?)

The configuration should be set in config.yml. My proposition is to add a new property: submission.importExternal.viewMode.

Describe alternatives or workarounds you've considered

Currently, there's no way to see the actual metadatafield names in the preview modal besides inspecting the response from the /api/integration/externalsources/{{source}}/entries. They're not even listed inside class/id attributes.

Additional information

Nothing to add

[MMilosz]

Assigning to myself, I'll push a PR in a moment

EDIT: something happened with my npm command... I added the PR as a draft

EDIT2: done, PR is ready! Had to reinstall npm, some 'missing shared libraries' errors