Support for image page icons

[mxstbr]

When uploading an image as a page icon it breaks when rendered.

Here's what it looks like in Notion:

Here's what it looks like when rendered with react-notion:

[mxstbr]

Here's the error that the image page shows when visited directly:

{"errorId":"...","name":"ValidationError","message":"For secure file URLs, must specify table and id."}