Products compare GraphQL schema

[lenaorobei]

Goal

Implement products compare GraphQL functionality.

Solution

Proposed by @kisroman schema and interfaces in following PRs:

• graphQl-200: Product Compare magento2#23704
• GraphQl-200: Product Compare graphql-ce#338

Requested Reviewers

@paliarush
@akaplya

[kisroman]

1. First I added new field hashed_id for every compare list to give ability get data by field hashed_id. This field is generating like quote id masked.
2. I added one query compareProductsList - query to get compare list by hashed_id.
3. Three mutation ware added: addProductToCompareList, removeProductFromCompareList, createCompareList.
   First createCompareList needed to be used to get hashed_id for compare list. It returns CreateCompareListOutput with hashed_id .
   addProductToCompareList is used with hashed_id and addProductToCompareListInput . addProductToCompareListInput contains ids - product ids to add to compare list.
   removeProductFromCompareList is used with hashed_id and removeProductFromCompareListInput. removeProductFromCompareListInput contains ids - product ids to remove from compare list.

[sivaschenko]

@lenaorobei @kisroman @akaplya @paliarush was this proposition reviewed? What is the decision?

[lenaorobei]

It was closed in favor of https://github.com/magento/architecture/blob/master/design-documents/graph-ql/coverage/catalog/compare-list.md