Add a method to check whether an application is qualified to export virtual assist node to ccapi

Test: atest android.view.contentcapture.LoginTest#testNotifyVirtualChildrenAppearedWithCustomView_100
Flag: android.view.contentcapture.flags.enable_export_assist_virtual_node_to_ccapi
Bug: 430421182
Change-Id: Id798af300e663baa74f463c0765e2c0c40ac7b0b