Problem/Motivation
In fixing #3066802: Ensure that embedded image media items do not display at unreasonable sizes by default, we realized that, once that issue is in, adding a new media type with the "Image" source will automatically create a nice, pared-down default display or that media type, which just shows the source field.
However, this same nicety doesn't apply to other media types -- if you create, say, a new Remote Video media type, you'll get a bunch of other additional fields (none of which are likely to be as useful to a user as the source field) by default. That kind of sucks.
Proposed resolution
All new media types should, by default, show only the source field in their default display.
Remaining tasks
Fix this for all media types and write tests, then commit the patch.
User interface changes
TBD, likely none.
API changes
None.
Data model changes
None.
Release notes snippet
TBD