Add unit tests for kiosk mode dialog

Adding a new unit tests to check that when kiosk mode is enabled,
certain UI elements of the dialog are not visible

Bug: 429288575
Flag: com.android.window.flags.enable_updated_display_connection_dialog
Test: ExternalDisplayConnectionDialogDelegateTest
Change-Id: I2a1f58b0d1c4e1716b5bda73ed42d94412dce13f