[ROSP] Add support for multiple chip icons

This CL adds support for more than one icon to be shown in the
StatusBarPopupChip. For starters, it will be used by the AvControlsChip
status chip to display a mic and camera icon.

Bug: 406518844
Test: Make sure the media control chip behavior is unchanged
Flag: com.android.systemui.status_bar_popup_chips

Change-Id: I203435d960304057d9b893249d75dba49de42fc0