[3/N] Store freeform bounds on disconnect.

Stores display uniqueIds on display connect to use for the purpose of preserving desktop displays. When a disconnect event happens in DesktopTasksController, record the bounds of all tasks present in the desks on the disconnected display. These preserved displays will be used in a future CL to restore desktops if the same display is reconnected.

Bug: 365873835
Test: Disconnect a display, debug repository state.
Flag: com.android.window.flags.enable_display_disconnect_interaction
Flag: com.android.window.flags.enable_display_reconnect_interaction

Change-Id: I2dfb977bedaa1fa09e56fa05c79071c0befd3aeb