Change SLA pricing to use price lists

As business user I would like to utilise pricing framework to support Carrier SLA pricing strategies.

At the moment Carrier SLA pricing uses separate pricing mechanism which is very limited. There is only option to select basic price or 'free'. Price List API is SKU agnostic. It is also much richer as it allows to set quantity tier, regular and sale prices. Further more multiple price definition can be set at once. Moreover we can easily reuse priceService and promotionServices as is with no effort. Additionally there is also opportunity to unitise quantity tier which may add extra context to the price such as "weight level" or "volume level" etc.