BasicShellCommandHandler is used by mainline modules and the
framwork. There is a new repo that was created for putting
this kind of utility class. Move BasicShellCommandHandler for
the incoming ConnectivityService mainline and updating the
related usage.
Bug: 170598012
Test: m ; verify with adb shell cmd
Change-Id: I8a2873df6e7d8342b7a8b466bda155f74c807ee3
Merged-In: Ida30c877116090616d4bf3f87fdad835446dac84
d5726c1916