For misspelled enums or field names, these suggestions can be helpful.
This also changes the suggestions algorithm to better detect case-sensitivity mistakes, which are common
ref: graphql/graphql-js#1153
This is a fairly major refactoring of coerceValue which returns an Either so it can return a complete collection of errors. This allows originalError to be preserved for scalar coercion errors and ensures *all* errors are represented in the response.
This had a minor change to the logic in execute / subscribe to allow for buildExecutionContext to abrupt complete with multiple errors.
ref: graphql/graphql-js#1133
