Remove dependency on fast-json-stable-stringify.

> Note: I am expecting tests to fail for this commit, demonstrating the
importance of using a stable serialization strategy for field arguments.

Although fast-json-stable-stringify has done its job well, it only
provides a "main" field in its package.json file, pointing to a CommonJS
entry point, and does not appear to export any ECMAScript modules.

Thanks to our conversion/abandonment of fast-json-stable-stringify and
other CommonJS-only npm dependencies (zen-observable in #5961 and
graphql-tag in #6074), it should now (after this PR is merged) be
possible to load @apollo/client/core from an ESM-aware CDN like
jsdelivr.net or jspm.io:

  <script type=module
    src="https://cdn.jsdelivr.net/npm/@apollo/client@beta/core/+esm">
  </script>

If you put that script tag in an HTML file, or inject it into the DOM of
any webpage, you will currently see this error:

  Uncaught SyntaxError: The requested module
  '/npm/fast-json-stable-stringify@2.1.0/+esm' does not provide an
  export named 'default'

This list of errors used to be longer, but now the only package left is
fast-json-stable-stringify.

Note that we're loading @apollo/client/core@beta here, not
@apollo/client@beta. The reason @apollo/client itself is not yet
ESM-ready is that react and react-dom are the two remaining
CommonJS-only dependencies, and @apollo/client currently/regrettably
re-exports utilities from @apollo/client/react.

If importing from @apollo/client/core is a burden or feels weird to you,
please know that we are planning to make @apollo/client synonymous with
@apollo/client/core in Apollo Client 4.0, along with making
@apollo/client/react synonymous with the v3 API of @apollo/client,
though of course those will be major breaking changes:
#8190

package.json

@@ -76,7 +76,6 @@
     "@wry/context": "^0.6.0",
     "@wry/equality": "^0.4.0",
     "@wry/trie": "^0.3.0",
-    "fast-json-stable-stringify": "^2.0.0",
     "graphql-tag": "^2.12.3",
     "hoist-non-react-statics": "^3.3.2",
     "optimism": "^0.16.1",

src/utilities/graphql/storeUtils.ts

@@ -17,7 +17,6 @@ import {
   SelectionSetNode,
 } from 'graphql';
 
-import stringify from 'fast-json-stable-stringify';
 import { InvariantError } from 'ts-invariant';
 import { FragmentMap, getFragmentFromSelection } from './fragments';
 
@@ -181,6 +180,7 @@ export function getStoreKeyName(
   fieldName: string,
   args?: Record<string, any> | null,
   directives?: Directives,
+  stringify: (value: any) => string = JSON.stringify,
 ): string {
   if (
     args &&
@@ -202,7 +202,7 @@ export function getStoreKeyName(
         filteredArgs[key] = args[key];
       });
 
-      return `${directives['connection']['key']}(${JSON.stringify(
+      return `${directives['connection']['key']}(${stringify(
         filteredArgs,
       )})`;
     } else {
@@ -224,7 +224,7 @@ export function getStoreKeyName(
     Object.keys(directives).forEach(key => {
       if (KNOWN_DIRECTIVES.indexOf(key) !== -1) return;
       if (directives[key] && Object.keys(directives[key]).length) {
-        completeFieldName += `@${key}(${JSON.stringify(directives[key])})`;
+        completeFieldName += `@${key}(${stringify(directives[key])})`;
       } else {
         completeFieldName += `@${key}`;
       }