[PiP on CD] Adjust rounded corners radius

for the current display, after the current display is updated in
PipDisplayLayoutState.

Also add a DisplayIdListener interface to inform PiP classes of display
id changes in PipDisplayLayoutState.

Recall: http://recall/clips/3e525e7a-06af-499a-9767-ccca7da0921b

Bug: 416788909
Test: atest WMShellUnitTests:com.android.wm.shell.pip2
Test: atest WMShellUnitTests:com.android.wm.shell.pip
Test: atest WMShellUnitTests:com.android.wm.shell.common.pip
Test: Manual - enter PiP on external display, verify that rounded
corners are scaled
Flag: com.android.window.flags.enable_connected_displays_pip

Change-Id: Id6417848341efc7bf2ab531444ae9d8fee8b99dd