Re-export cache types from @apollo/client/core, again. (#6725)

These types were lost in #6656 when I switched from

  export * from '../cache'

to using named exports. There are some @apollo/client/cache exports that I
wanted to omit from @apollo/client/core (like cacheSlot), but I definitely
did not intend to omit these types.

Fixes #6723.

src/core/index.ts

@@ -34,14 +34,29 @@ export { isApolloError, ApolloError } from '../errors';
 /* Cache */
 
 export {
+  // All the exports (types and values) from ../cache, minus cacheSlot,
+  // which we want to keep semi-private.
   Cache,
   ApolloCache,
+  Transaction,
+  DataProxy,
   InMemoryCache,
+  InMemoryCacheConfig,
   MissingFieldError,
   defaultDataIdFromObject,
+  ReactiveVar,
   makeVar,
+  TypePolicies,
+  TypePolicy,
+  FieldPolicy,
+  FieldReadFunction,
+  FieldMergeFunction,
+  FieldFunctionOptions,
+  PossibleTypesMap,
 } from '../cache';
 
+export * from '../cache/inmemory/types';
+
 /* Link */
 
 export * from '../link/core';