Fix Safari/iOS unable to load some images in the app

[4ian]

This needs testing to check that the web-app works properly for these cases.

Thumbnails from examples work properly:

• [ ] on Safari iOS
• [ ] on Safari macOS
• [ ] on Chrome/Firefox as before

Assets are displayed on the asset store:

• [ ] on Safari iOS
• [ ] on Safari macOS
• [ ] on Chrome/Firefox as before

Assets are displayed in the scene editor:

• [ ] on Safari iOS
• [ ] on Safari macOS
• [ ] on Chrome/Firefox as before

Previews run properly:

• [ ] on Safari iOS
• [ ] on Safari macOS
• [ ] on Chrome/Firefox as before

Export run properly:

• [ ] on Safari iOS
• [ ] on Safari macOS
• [ ] on Chrome/Firefox as before

[4ian]

Testing version is being deployed on https://editor-beta.gdevelop.io.

[ClementPasteau]

@4ian with the work you're currently doing on resources, is this PR still relevant?

[4ian]

I think we can merge this now as it should not make things worse/could actually improve stuff on Safari. And this change will be necessary for supporting resources uploaded on GDevelop Cloud, so let's have it now!