Taskbar on home should open all apps that support drag to workspace

If taskbar is shown on home screen, have the taskbar all apps button
toggle the launcher activity version of all apps UI. This makes the
behavior consistent with how all apps system action (keyboard shortcut)
works, and addresses a gap in functionality where users are unable to
drag apps from the taskbar all apps UI to the workspace.

Bug: 392118517
Flag: com.android.window.flags.enter_desktop_by_default_on_freeform_displays
Test: On desktop device, toggle all apps from taskbar on home screen,
      drag and app from all apps to workspace.
Change-Id: Ida0f230bf38c6e1e35041556f33de1be85daf785