[orm] hydrate fetched objects that are known in pool/identifymap

[marcj]

https://github.com/deepkit/deepkit-framework/blob/64cc55e812a6be555515e036de4e6b18d147b4f0/packages/orm-integration/src/bookstore.ts#L714 bookstore:multipleJoins:

        {
            const review = await database.query(Review)
                .innerJoinWith('book')
                .innerJoinWith('user')
                .findOne();
            console.log('review', review);
            console.log('review.user', review.user);
            expect(review.user.id).toBe(user.id);
            expect(review.book.id).toBe(book.id);
            // author became hydrated since we loaded the full user object also
            expect(review.book.author.name).toBe('Peter');
            expect(review.user.name).toBe('Peter');
            expect(review.book.title).toBe('Great');
            expect(review.status).toBe(ReviewStatus.hidden);
        }

since review.user === review.book.user and user is joined (fully loaded) it's necessary that both objects are the same. currently review.book.author is a unhydrated reference. the reference should hydrate as soon as the full user is found. we have the reference in formatter pool.

Also as soon as identity map is enabled for this query the formatter breaks. concretely: review.user becomes a reference and is never hydrated because it was first found in review.book.author as reference and stays a reference. we need to check first for pool then identitymap (identitymap alone is not hydrated when new information is available)