Create utility for `bmgr transport -c` command and output parsing in BackupUtils.

Using the "-c" flag to use the new async variant, which might help address race condition of transport registration.

https://android-build.corp.google.com/abtd/run/L24700030017689122/

Test: See bug ticket for abtd/ runs
Bug: 440699841

Change-Id: I18297dace8f0b1f218b96599e0f0ca4c80a1a5af
1 file changed