Expose internal representation of transport types. am: a25fdeb1c7

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/23720719

Change-Id: I5b82ddc75093f93ed2885d4ec09ef25bd3768bab
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>