AVIF Image Format Support

[Nawor3565]

Describe the feature you'd like

Since the AVIF format now seems to be well supported among browsers, it would be useful to add support for the format to Bookstack. In fact, it seems like the format may already be functional as AVIF images are displayed in the "image format not supported" error pop-up when trying to upload one, so adding support may be trivial.

Describe the benefits this would bring to existing BookStack users

Support for a modern, high-qualify image compression format that is becoming more widely used

Can the goal of this request already be achieved via other means?

No, because this is a very specific request.

Have you searched for an existing open/closed issue?

• I have searched for existing issues and none cover my fundamental request

How long have you been using BookStack?

1 to 5 years

Additional context

It was recommended that I open a new request for this in #2505