Add the ability to override the title of the 'Quantity' field on the product form

I had the need to have a custom title for the 'Quantity' field. It was hardcoded to 'Quantity' (which probably works in 99% of cases) but I needed to make it say something else.

Im not sure if this is the best approach since its very specific to the Quantity field and doesn't allow overriding and of the other field names. Could this approach be followed for other field names (eg, define a method for getting the title of each field name) or is there a better way?