The buttons to add site icons, logos, header images, and background images were designed with a dashed border. This led to confusion with users thinking they were drop regions for image uploads, rather than buttons to trigger an upload.
Change design of upload buttons to clarify expected user interaction.
Props emaildano, afercia, joedolson, ankitkumarshah, logicrays, shailu25.
Fixes#47579.
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