Package export does not prompt any UI action after completion with V16 schema / local.properties::legacy_schema=false

[mikehardy]

Issues with non-legacy schema:

• I'm not sure where exporting a deck drops the apkg? It did not pop up a prompt or anything (import of new shared deck worked though...)

Wiith legacy schema, the UI prompts you to save the file etc. Apparently in new schema the path to the file is displayed in logcat so it is probably a matter of hooking up the API with the new backend import/export work from #11644

Originally posted by @mikehardy in #11644 (comment)