[product/ERP5Type] Introduce Log.py for compatibility
Without it, it is not possible to upgrade instances since: https://lab.nexedi.com/nexedi/erp5/commit/48c45fbdd8fa30799ef1b9e6ad2e1e5cb8415487
Without it, it is not possible to upgrade instances since: https://lab.nexedi.com/nexedi/erp5/commit/48c45fbdd8fa30799ef1b9e6ad2e1e5cb8415487