Allow upload of SVG images

[andrixnet]

Feature request: image uploader (cache description, logs) to also allow SVG images to be uploaded, used and displayed.

Currently in edit cache image uploader recognizes SVG as image, puts into the upload queue, but it does not get loaded to the cache.

[stefopl]

SVG can be unsafe because it’s an XML file that, besides graphics, can contain JavaScript, external resource references, or embedded data, enabling XSS. It should therefore be thoroughly sanitized or converted to PNG.
By the way, there may also be issues when trying to upload TIFF/HEIF, as I’ve seen that in the logs before.

[andrixnet]

Regarding SVG I'd say sanitized rather then conversion, if it can be done reasonably.
Regarding TIFF, which is not a wide spread web graphic format, I'd leave it to be referenced by other means, besides, usually they are BIG files.
Regarding HEIF and WEBP, if there are no other considerations (such as those for SVG), I'd vote to support them.