gn2bp: Add `get_cmd` logic. am: c739dda3f1

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/2325457

Change-Id: I580abde11a308adf66b19b0cda280d59f2aa7151
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>