Choose Image types & Accept GIF, SVG & WEBP types

[trymeouteh]

Please add a setting to choose what image MIME types will be accept in the image upload button. This way we can decide to only allow JPEG or allow JPEG and PNG.

And please also expand on the image types to include GIF, SVG and WEBP types.

[trymeouteh]

#4592 Pull request expands the accepted images for being upload to jpeg, png, gif, webp and svg