Ability to upload emoji without shortcode

Now we must provide shortcode when uploading a new emoji. Due to this feature request I need to be able to upload emoji without shortcode, we can infer shortcode from the filename.

Also now POST /api/pleroma/emoji/packs/:name/update_file returns all emojis in the pack which makes it hard to distinguish which emoji was uploaded. Can we please make this endpoint always return only information about single uploaded/updated/removed emoji.