crm_rma_stock_location: adds a RMA location on warehouses

Then, display 'Quantity on Hand' and 'Forecasted Quantity'
fields based on this location and its children locations.

The lot_rma_id field on stock.warehouse has been extracted from
crm_rma_advance_location so that now crm_rma_stock_location is a dependency for
crm_rma_advance_location.