[IMP] *: rename image fields

image_original => image_1920 (now resized to 1920)
image_big => image_1024
image_large => image_256
image_medium => image_128
image_small  => image_64
image replaced by image_1920 (when writing) or by image_1024 (when displaying
	what was previously the big size)

+ add new intermediate format:
image_512

PR: #34925

addons/web/static/src/js/fields/basic_fields.js

@@ -1833,7 +1833,7 @@ var FieldBinaryImage = AbstractFieldBinary.extend({
                     this.$el.addClass(this.attrs.class);
                 }
 
-                var urlThumb = this._getImageUrl(this.model, this.res_id, 'image_medium', unique);
+                var urlThumb = this._getImageUrl(this.model, this.res_id, 'image_128', unique);
 
                 this.$el.empty();
                 $img = this.$el;