[Test] Built-in image preview extension

[mjbvz]

Test for #81672

• Mac @sbatten
• Linux @sandy081
• Windows @deepak1556

Complexity: 4

Overview

Our image preview code has been moved out of core and into a built-in extension. This extension uses our custom editor api to implement the image preview. It should have the same basic functionality as the old image preview, although some of the details may work slightly differently.

Testing

• You can correctly view a variety of common image formats: png, gif, jpg, tiff, bmp, ico, ...
• Zooming works and is preserved when you switch away from the image preview and back to it
• The status bar shows the current zoom level. You can click in the status bar to change the zoom level
• The image preview works in remote cases
• You can disable the built-in image preview. In this case, you should see our normal binary editor
• If you view a large image in the remote case, we should show a loading indicator in the editor
• Changing themes works as expected
• The built-in image preview's extension page fits with our other extensions