[FIX] web: display 0 for FieldFloatToggle

The field was hidden in UI when its value was not set or equal to 0.

Display the field if its value is set to 0.

[IMP] web: clean code

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

@@ -1287,7 +1287,14 @@ var FieldFloatToggle = AbstractField.extend({
             this._setValue(next_val); // will be parsed in _setValue
         }
     },
-
+    /**
+     * For float toggle fields, 0 is a valid value.
+     *
+     * @override
+     */
+    isSet: function () {
+        return this.value === 0 || this._super(...arguments);
+    },
 });
 
 var FieldPercentage = FieldFloat.extend({