Wrong image URI when content name has extended UTF characters

When a content (e.g article) has a name that includes extended characters (e.g. À,ß,Ç, etc) and an image is uploaded into an ezimage FieldType, the image URI is wrong.

Steps to reproduce:

• Start by editing site.ini.append.php and adding:

[URLTranslator]
TransformationGroup=urlalias_iri

• Clear legacy cache afterwards;

Case 1:

1. Create an article called "ÀßÇЀƒ" and upload an image to the "Image" field;
2. Open the article in the frontend and check the image URI: example.com/var/ezdemo_site/storage/images/tests/àßçð€ƒ/712-1-eng-GB/_articleimage.png

This is wrong. The image name is "_articleimage.png", should be "ÀßÇЀƒ_articleimage.png"

Case 2:

1. Create an article called "ÀßÇ.Ѐƒ" and upload an image to the "Image" field (note the dot between "ÀßÇ" and "Ѐƒ");
2. Open the article in the frontend and check the image URI: example.com/var/ezdemo_site/storage/images/tests/àßç.ð€ƒ/712-1-eng-GB/.Ѐƒ_articleimage.png

This is wrong. The image name is ".Ѐƒ_articleimage.png", should be "ÀßÇ.Ѐƒ_articleimage.png"