Merge "Revert "Revert "Add VpnServiceBuilderShim for VpnService.Builder""" am: a9d1ef600c

Original change: https://android-review.googlesource.com/c/platform/packages/modules/NetworkStack/+/1931759

Change-Id: Ib7ca0c7edd229b2446afeacd07b6188e8699bf9d