Apollo Federation composition check

**Is your feature request related to a problem? Please describe.**

I am using apollo federation. However, it seems like there is no way to validate the composition of schemas during compile time. One has to push all the service schemas to the apollo registry to validate the composition.

**Describe the solution you'd like**
Check any composition error when running codegen. I know that federation is currently being worked on by the maintainers. This would be a great feature to have!!