Moved Maybe to jsutils folder and remove tsutils

[IvanGoncharov]

No description provided.

[wodka]

This change breaks Apollo Server

node_modules/@apollo/federation/dist/composition/utils.d.ts:3:19
  error TS2307: Cannot find module 'graphql/tsutils/Maybe' or its corresponding type declarations.

import Maybe from 'graphql/tsutils/Maybe';

[IvanGoncharov]

@wodka Thanks for reporting 👍
It is an internal type not intended to be used outside of our package that is why it's not exported through intex.d.ts.
Can you please report it to the Apollo team?