Refactor markMutationResult function in order to export it
Refactor markMutationResult function in order to export it

This commit, through a small refactor, allows you to export the functions
that implement the cache update logics following a mutation.

The main changes:
  * creation of the public method `generateUpdateQueriesInfo` in QueryManager
  * removal of the generateUpdateQueriesInfo constant within the mutate function
  * creation & export of the `markMutationOptimistic` function
  * refactor & export of the `markMutationResult` function, the main
    change is the addition of the queryManager parameter in order to use the
    generateUpdateQueriesInfo function

apollographql/apollo-client,apollographql/apollo-client