title: MatSelect ntegration testing
body: <p>I want to test my component that uses mat-select.
  I have to trigger openedChange event with value == true so I can proceed to get options for select
  Tried like this</p>
  <pre><code>    const selectHarness = await loader.getHarness&lt;MatSelectHarness&gt;(MatSelectHarness);
      await selectHarness.open()
  </code></pre>
  <p>or this way</p>
  <pre><code>const matSelect = debugElement.query(By.css('.mat-select-trigger')).nativeElement;
  matSelect.click();
  </code></pre>
  <p>or this way</p>
  <pre><code>fixture.debugElement.query(By.css('mat-form-field')).triggerEventHandler('selectionChange', { value: true });
  
  
  @ViewChild(MatSelect, { static: false }) select!: MatSelect;
  </code></pre>
  <p>...</p>
  <pre><code>this.select.openedChange
    .subscribe((value: boolean) =&gt; {
      if (value) {
        this.subscribeToSearchInput();
        this.focusInput();
        this.registerPanelScrollEvent()
        this.subscribeToLoadOptions();
      } else
        this.inputSubscribtion?.unsubscribe();
    })
  </code></pre>