Allow clearing instant app meta-data

The package manager has an API to clear the data of an app
which does not work for uninstalled instant apps for which
we store some meta-data (icon, title, cookie). This change
allows clearing the data of an uninstalled instant app.

Test: Instant cookie CTS tests use this API

bug:64517837

Change-Id: Ia929fead71b5ae786e88ddd0fa8e8a490d970dd0