Trigger the translations on the duplicate operation

Problem/Motivation

Translations are not available on the duplicate operation.

In \Drupal\inline_translation\EntityOperations::entityFormAlter(),

if (!in_array($form_object->getOperation(), ['add', 'edit', 'default'], TRUE)) {

we are not adding the duplicate operation.

Proposed resolution

Add the duplicate operation like so,

if (!in_array($form_object->getOperation(), ['add', 'edit', 'duplicate', 'default'], TRUE)) {