Ajax dialog button handling should be more flexible

This issue is being reviewed by the kind folks in Slack, #needs-review-queue-initiative. We are working to keep the size of Needs Review queue [2700+ issues] to around 400 (1 month or less), following Review a patch or merge request → as a guide.

Unfortunately, that breaks the Media Library, and therefore necessitated an unfortunate workaround.

This makes it sound like a bug no? Think test coverage will be needed.

I encountered this problem while using Layout Paragraphs module. Fields with unlimited value fields would have their "Add More" buttons moved into the dialog button pane. The suggestion from #13 didn't solve the issue.

What I did find to solve my specific problem was to just provide an overridden template for the field-multiple-value-form.html.twig. In the Claro theme, the "Add More" button is wrapped with the form-actions class. So I simply remove that from the template and it solves the problem with fields.

PAtch #13 does not apply to D10.2.2 anymore. Attached the patch without functional changes

Sorry #17 had a wrong base, patch corrected