Ps/improve state provider fakers (#7494)

* Expand state provider fakes

- default null initial value for fake states
- Easier mocking of key definitions through just the use of key names
  - allows for not exporting KeyDefinition as long as the key doesn't collide
- mock of fake state provider to verify `get` calls
- `nextMock` for use of the fn mock matchers on emissions of `state$`
- `FakeAccountService` which allows for easy initialization and working with account switching

* Small bug fix for cache key collision on key definitions unique by only storage location

* Fix initial value for test

libs/common/src/platform/state/implementations/default-state.provider.spec.ts

@@ -1,5 +1,6 @@
 import { of } from "rxjs";
 
+import { FakeAccountService, mockAccountServiceWith } from "../../../../spec/fake-account-service";
 import {
   FakeActiveUserStateProvider,
   FakeDerivedStateProvider,
@@ -19,9 +20,11 @@ describe("DefaultStateProvider", () => {
   let singleUserStateProvider: FakeSingleUserStateProvider;
   let globalStateProvider: FakeGlobalStateProvider;
   let derivedStateProvider: FakeDerivedStateProvider;
+  let accountService: FakeAccountService;
 
   beforeEach(() => {
-    activeUserStateProvider = new FakeActiveUserStateProvider();
+    accountService = mockAccountServiceWith("fakeUserId" as UserId);
+    activeUserStateProvider = new FakeActiveUserStateProvider(accountService);
     singleUserStateProvider = new FakeSingleUserStateProvider();
     globalStateProvider = new FakeGlobalStateProvider();
     derivedStateProvider = new FakeDerivedStateProvider();