Save cart item refactor

• refactor SaveCartItem resolver
• add new Input Type for GraphQl (to be used in the future)
• fixed add to cart functionality, that was causing qty change to trigger item re-adding to the cart

Release: Implemented taxation support

In this release the taxation implementation was fixed, previously the tax_amount field was always returning null.

Minor improvements

• Add event listener for e-mail sending, when order is submitted over GraphQl.
• Change composer require to magento2-base for EE/CE version compatibility

Patch: Fixed discount calculation

In this release the missing observer was added, in order to fix scandipwa/scandipwa#216

Patch: 2.0.3 changes merged with 2.0.2 cheanged

This patch is a fix, for a mistake that leaded to configurable product fix patch 2.0.2 not working together with 2.0.3 changes.

[BROKEN] Patch: Fixed estimate shipping cost for logged in customers

Merge pull request #3 from niksKozlovs/master

Fixed estimae shipping cost bug

Patch: Fixed configurable product adding to cart

2.0.2

Fixed configurable product adding to cart

Removed `getCartItems` added `getCartForCustomer`

In this release:

• Following query was added getCartForCustomer. It's main goal is to get full cart data, including totals, items, and products related to returned item.
• Following query was removed getCartItems due it's functional being present in getCartForCustomer.
• Mutation saveCartItem was updated to update totals on item save (related to M2 core bug: https://github.com/magento/magengto2/issues/2991)

Release: Mutation update, to allow sequential query of cart details

In this release multiple schema parts were altered, to return a Query. The internal implementation has also been altered. This was done, so you can update the cart and immediately request totals. Here is the list of changed mutation:

• saveCartItem
• removeCartItem
• getCartForCustomer

The new query was added to replace the old one getCartItems query. The new one includes totals and other valuable information in it: getCartForCustomer .

From this release the real totals are being displayed in the cart.