[IMP] web: add support for itemprop on img

Take the following QWeb snippet:

```
<div t-field="product.image" itemprop="image" t-options="{'widget': 'image'}"/>
```

When the image is rendered, the `itemprop="image"` remains on the
`<div>` tag, it is not set on the `<img>` tag.

We add the support of the `itemprop` option, so it can be added to the
`<img>` tag:

```
<div t-field="product.image" t-options="{'widget': 'image', 'itemprop': 'image'}"/>
```

opw-2076934

addons/web/models/ir_qweb.py

@@ -69,8 +69,13 @@ class Image(models.AbstractModel):
         elif options.get('zoom'):
             src_zoom = options['zoom']
 
+        itemprop = None
+        if options.get('itemprop'):
+            itemprop = options['itemprop']
+
         atts = OrderedDict()
         atts["src"] = src
+        atts["itemprop"] = itemprop
         atts["class"] = classes
         atts["style"] = options.get('style')
         atts["alt"] = alt