Improve the focus behaviour after clicking 'Save and select' in the media library.

Problem/Motivation

This is a follow-up of #2988431: [Meta] Accessibility plan for Media Library Widget. We have 2 remarks about where to shift the focus after adding new media items in the media library:

• After adding a new media item the focus shift to the dialog instead of the form of the added media item.
• After saving the new media item, the focus is set on the dialog. I would expect that the focus is shifted to the added item in the selection.

We already have implemented changes for the focus for the 'Insert selected' and the 'Save and insert' buttons, but not for the 'Save and select' button of the add form.

Proposed resolution

Improve the focus behaviour after clicking 'Save and select' in the media library.

Remaining tasks

1. Choose where to shift the focus after 'Save and select'.
2. Write a patch.
3. Review.
4. Commit.

User interface changes

None

API changes

None

Data model changes

None

Release notes snippet