Remove import of apollo-env.

We're only importing `apollo-env`, which is primarily a polyfill library,
for one of its helper utilities.  Inlining these few lines seems like a win.

(The import removed from the `RemoteGraphQLDataSource.test.ts` test was
unused.)

gateway-js/package.json

@@ -23,7 +23,6 @@
     "@apollo/query-planner-wasm": "0.0.2",
     "@types/node-fetch": "2.5.4",
     "apollo-engine-reporting-protobuf": "^0.5.2",
-    "apollo-env": "^0.6.1",
     "apollo-graphql": "^0.6.0",
     "apollo-server-caching": "^0.5.2",
     "apollo-server-core": "^2.17.0",

gateway-js/src/datasources/__tests__/RemoteGraphQLDataSource.test.ts

@@ -9,7 +9,6 @@ import {
 import { RemoteGraphQLDataSource } from '../RemoteGraphQLDataSource';
 import { Headers } from 'apollo-server-env';
 import { GraphQLRequestContext } from 'apollo-server-types';
-import { Response } from '../../../../../../apollo-tooling/packages/apollo-env/lib';
 
 beforeEach(() => {
   fetch.mockReset();

gateway-js/src/utilities/array.ts

@@ -1,4 +1,8 @@
-import { isNotNullOrUndefined } from 'apollo-env';
+function isNotNullOrUndefined<T>(
+  value: T | null | undefined,
+): value is T {
+  return value !== null && typeof value !== 'undefined';
+}
 
 export function compactMap<T, U>(
   array: T[],