Autotest: Refactor RPM Client code into its own module

Instead of having everything in autotest need a host to interact with
an RPM, this code is now refactored into its own module.

BUG=None
TEST=local system

Change-Id: If9b173009eeb9d791e41947a103b59cc78fc3806
CQ-DEPENDS: I0a21086a6d33adce456bcb512e9a3823e7584058
Reviewed-on: https://gerrit.chromium.org/gerrit/38434
Commit-Ready: Simran Basi <sbasi@chromium.org>
Reviewed-by: Simran Basi <sbasi@chromium.org>
Tested-by: Simran Basi <sbasi@chromium.org>
2 files changed