[IMP] mrp: make the MO on the WO readonly

Part of: https://github.com/odoo/odoo/pull/54283


task-2278147

closes odoo/odoo#54607

X-original-commit: b13e7d7bf3565242d1f99c6d9d5dfc7a8aa2929d
Related: odoo/enterprise#11906
Signed-off-by: Arnold Moyaux <amoyaux@users.noreply.github.com>