[REF] *stock*: rename model `stock.production.lot` into `stock.lot`

addons/mrp/data/mrp_demo.xml

addons/mrp/models/__init__.py

addons/mrp/models/mrp_production.py

addons/mrp/models/mrp_unbuild.py

addons/mrp/models/mrp_workorder.py

addons/mrp/models/stock_lot.py

addons/mrp/models/stock_move.py

addons/mrp/tests/test_backorder.py

addons/mrp/tests/test_multicompany.py

addons/mrp/tests/test_order.py

addons/mrp/tests/test_stock.py

addons/mrp/tests/test_traceability.py

addons/mrp/tests/test_unbuild.py

addons/mrp/wizard/stock_assign_serial_numbers.py

addons/mrp_product_expiry/tests/test_mrp_product_expiry.py

addons/mrp_repair/tests/test_tracability.py

addons/mrp_subcontracting/tests/test_subcontracting.py

...bcontracting_account/tests/test_subcontracting_account.py

addons/point_of_sale/models/pos_order.py

addons/point_of_sale/models/stock_picking.py