**What**
- validate shipping option requirements including tax if the shipping option is tax inclusive
**Testing**
- " given a cart with total above min-threshold and subtotal below min-threshold shipping option with tax inclusive pricing is available and can be applied"
- "given a cart with total above max-threshold and subtotal below max-threshold shipping option with tax inclusive pricing is not available"
Fixes CORE-752
add: composite unique constraint for shipping_option_id and cart_id
fix: fetchCartOptions to format custom shipping options like normal shipping options
fix: addShippingMethod should throw when custom shipping options is not empty and no optionId corresponds to custom shipping options