Improving type safety

@phryneas had the idea of installing several minor versions of AC under difference package aliases to verify that we don't break integrations with old versions of Apollo Client, after we remove all of the `any`s and set `noImplicityAnys` to true.

Start by reviewing the TypeScript configuration and locating the `any` usages involved in Apollo Client integration. Verify compatibility by installing several minor Apollo Client versions under different package aliases, then confirm that implicit anys are disabled and older integrations remain working.

Written by the indexing model from the issue text.