Show popup warning to librarians when they've populated fields that have an "add" button but forgot to use the button

### Problem

Most form fields on work, edition or author pages are just saved when I click "save". However, some fields (e.g. add link to work) have an additional "add" button that needs to be clicked before saving. I keep forgetting to use that button, and the input to that form field is lost.

### A clear and concise description of what you want to happen

Whenever I populate a form field that has an "add button" and then save that page without having used the "add" button, I would like to see a warning.

### Expected behaviour / screenshots (ex: Figma design screenshots for UI feature)

### Additional Context

### Proposal & Constraints

### What is the proposed solution / implementation?

Show a popup warning whenever a form field with an add button has been populated but not saved. Or maybe just save the content, if that is possible.

### Is there a precedent of this approach succeeding elsewhere?

### Which suggestions or requirements should be considered for how feature needs to appear or be implemented?

### Leads

### Related files

### Stakeholders

### Instructions for Contributors

- Please [run these commands](https://github.com/internetarchive/openlibrary/wiki/Git-Cheat-Sheet#working-on-your-branch) to ensure your repository is up to date **before** [creating a new branch](https://github.com/internetarchive/openlibrary/wiki/Git-Cheat-Sheet#making-changes-and-creating-a-pull-request) to work on this issue and **each time after** pushing code to Github, because the pre-commit bot may add commits to your PRs upstream.

No related files, tests, or entry points are named. Begin by locating the work, edition, and author forms and the fields with add buttons; confirm the warning appears when populated values would otherwise be lost and that normal saves remain unaffected.

Written by the indexing model from the issue text.