Allow provisioning package to retrieve subGrp, clear it's own config

This changes the VCN to allow a VCN provisioning package to retrieve
its listing of configured subgroups and clear its own configurations,
regardless of whether it is the active subscription group.

Safety is guaranteed based on the VCN's clearing of packages when app
data is cleared, and when the app is uninstalled. In addition to the
configurations not being retrievable, the clearing of the configs will
ensure that sideloading of an app with the same package name provides
no ability to otherwise impact settings.

Bug: 227248744
Test: atest FrameworksVcnTests
Change-Id: I2c774c00373942f895169a761d4e9a1d5b0b2edb