[IMP] web: add decoration support for all field widgets (#25160)

It is sometimes useful to be able to customize slightly the color of a
field depending on some conditions on the current record.

For example, imagine that we want to show a VAT number field in green/red, if
it was validated or not. To do that, we can add a field with an
onchange, and simply add decoration-danger and decoration-success
attributes to the field.

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

@@ -206,6 +206,13 @@ var InputField = DebouncedField.extend({
             this.isDirty = false;
         }
         if (this.isDirty || (event && event.target === this && event.data.changes[this.name] === this.value)) {
+            if (this.attrs.decorations) {
+                // if a field is modified, then it could have triggered an onchange
+                // which changed some of its decorations. Since we bypass the
+                // render function, we need to apply decorations here to make
+                // sure they are recomputed.
+                this._applyDecorations();
+            }
             return $.when();
         } else {
             return this._render();