Insert from URL accepts plain text and assumes is an image blob

[johngodley]

Description

If you type some text into the 'insert from URL' dialog it then assumes it is an image blob, turns the block into a valid image, and lets you change settings and upload it the server.

Secondary to this, the upload icon appears even if hasUploadPermissions is false.

Step-by-step reproduction instructions

1. Add an image block
2. Click 'Insert from URL'
3. Enter a word like 'hello'
4. Submit and the block becomes a valid image block (i.e. you can change image settings). Also note that the 'upload external image' button is now available
5. Click the upload button and get undefined: Sorry, this file type is not supported here.

Screenshots, screen recording, code snippet

Environment info

• Gutenberg 14.7.0 RC 1
• WordPress 6.1

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes