Restore cts-suite hard check of interface

Ensure cts modules implements ITestFilterReceiver and throw
if they do not. (+presubmit enforcing).

Create an artificial root dir if CTS_ROOT is not present in
order to run CTS from Tradefed directly in some cases.
Test: unit tests,
run cts-suite -m CtsGesture
run cts-suite -m CtsGesture --use-sandbox
Bug: 65303193
Bug: 65303193

Change-Id: Ie937ab631aa34462c09bcd6de096493903937921
5 files changed