Added 'Exclude Sale Products' option to coupons

Added exclude sale products functionality based of the 'exclude product
ids' functionality in wc-coupon/wc-cart.

Compares product ID's in cart vs ID's in the array
'woocommerce_get_product_ids_on_sale'
idiotic missed semicolon

I cannot brain today, I has the dumb.
ditto
Updated everything so it actually works rather than fails hard

I messed up badly on the original with inheritance of variables, and
after a lot of issues realised that strict matching was necessary due
to the '0' string in woocommerce_get_products_on_sale()

Not hard to tell I am new to php.

Regardless this now functions as intended, stopping discount from being
applied to products with active sale prices or carts with items on sale
inside them.