b/418235689 Add a new test case for launching a new instance from long...

b/418235689 Add a new test case for launching a new instance from long pressing the app icon in the taskbar and tapping the new window.

Test: USE_RBE=false atest WMShellFlickerTestsDesktopMode:com.android.wm.shell.flicker.taskbar.LaunchNewInstanceFromTaskbarMenuFlickerTes -c (http://ab/I34200010444825127)
Video: http://recall/-/exKj704d5xnoH4PDW6SDAi
Flag: EXEMPT add new test case
Bug: 418235689

Change-Id: I09864991dcb1f472e926b8b1e7940537d80ed3c7