More test for taskbar overflow

Adds tests to TaskbarOverflowTests to verify that:
*   tapping overflow view toggles keyboard quick switch view
*   tasks associated with a hotseat item don't get added to
    recents taskbar section / overflow view
*   keyboard quick switch view shown from taskbar contains
    running tasks, excluding tasks associated with a hotseat item

Bug: 379774843
Flag: com.android.launcher3.taskbar_overflow
Test: atest TaskbarOverflowTest

Change-Id: Iee6316c33cef6322d567e853f9fa358b7af9e172