Shell: Make `RecentTasksController.getRecentTasks()` multi-desks aware

This CL changes `GroupedTaskInfo` and `RecentTasksController.getRecentTasks()`
such that multiple desktops are supported.

A companion Launcher CL is at ag/31825875, and a Car Launcher CL is at
ag/31837924.

Bug: 395911284
Test: m
Flag: com.android.window.flags.enable_multiple_desktops_frontend
Flag: com.android.window.flags.enable_multiple_desktops_backend
Change-Id: Ifc422e4a14f897170adb16572ce172a06c0b5304