[FIX] web: image widget is dependent on its record's last_update

As a way to optimize loading, images are not necessarily fetched in db.
They have, in their url a "unique" parameter, which is the last_update date on **the record** and controls on the python-side whether it should get the image from a cache or from the db.

Before this commit, this __last_update field wasn't present in the view, so it wasn't fetched, and writes on a model's image worked but did not refresh.
The image displayed was the old one.

After this commit, when the image field widget is present, we force the loading of the __last_update field of the record.
Upon update, the image displayed is the new one.

OPW 777552

closes #20457

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

@@ -21,6 +21,7 @@ var framework = require('web.framework');
 var session = require('web.session');
 var utils = require('web.utils');
 var view_dialogs = require('web.view_dialogs');
+var field_utils = require('web.field_utils');
 
 var qweb = core.qweb;
 var _t = core._t;
@@ -1127,6 +1128,10 @@ var AbstractFieldBinary = AbstractField.extend({
 });
 
 var FieldBinaryImage = AbstractFieldBinary.extend({
+    fieldDependencies: _.extend({}, AbstractFieldBinary.prototype.fieldDependencies, {
+        __last_update: {type: 'datetime'},
+    }),
+
     template: 'FieldBinaryImage',
     placeholder: "/web/static/src/img/placeholder.png",
     events: _.extend({}, AbstractFieldBinary.prototype.events, {
@@ -1149,7 +1154,7 @@ var FieldBinaryImage = AbstractFieldBinary.extend({
                     id: JSON.stringify(this.res_id),
                     field: this.nodeOptions.preview_image || this.name,
                     // unique forces a reload of the image when the record has been updated
-                    unique: (this.recordData.__last_update || '').replace(/[^0-9]/g, ''),
+                    unique: field_utils.format.datetime(this.recordData.__last_update).replace(/[^0-9]/g, ''),
                 });
             }
         }