[1/n] Add new EnableUpdatedDislpayConnectionDialog Flag

Introducing new flag for upcoming change to external display connection
dialog. This flag will allow new dialog to show on phones (or devices
that can do projected mode only, not extended mode).

Bug: 378688068
Test: EXEMPT new flag
Flag: com.android.window.flags.enable_updated_display_connection_dialog
Change-Id: I5c0360c8a592b79a64929f209db1fbc835f07331