[GraphQL] Use same type for mutations and queries if normalization context is equal

**Description**

[https://api-platform.com/docs/core/graphql/#different-types-when-using-different-serialization-groups](https://api-platform.com/docs/core/graphql/#different-types-when-using-different-serialization-groups)

In your documentation it states that if the normalization context is the same, then the generated type will be equal. However, looking at the TypeBuilder's code this appears to only be the case for collection_query and item_query. It would be nice if this was also the case for mutations and even custom mutations, because otherwise certain features of popular clients like Apollo don't work as expected (e.g. caching).