Add a new function to export virtual assist node to ccapi

Latency:
notifyVirtualChildrenAppearedWithCustomView_mean (ns): 9258196
notifyVirtualChildrenAppearedWithCustomView_median (ns): 9274098
notifyVirtualChildrenAppearedWithCustomView_min (ns): 9096326
notifyVirtualChildrenAppearedWithCustomView_standardDeviation: 138959

Test: atest android.view.contentcapture.LoginTest#testNotifyVirtualChildrenAppearedWithCustomView
Flag: android.view.contentcapture.flags.enable_export_assist_virtual_node_to_ccapi
Bug: 430421182

Change-Id: I97ab9b05e0f696a2e8cace3c04b1e439dee6ef9b