Adding timeout functionality/EnvVar to TestBed (#1044)

* Adding timeout functionality/EnvVar to TestBed
* updating timeout unit to microseconds

Signed-off-by: Tim Hu <timhu102@amd.com>

test/common/TestBed.cpp

@@ -296,6 +296,7 @@ namespace RcclUnitTesting
       {
         InteractiveWait("Starting ExecuteCollectives for child " + std::to_string(childId));
         PIPE_WRITE(childId, cmd);
+        PIPE_WRITE(childId, ev.timeoutUs);
         PIPE_WRITE(childId, useHipGraph);
         int tempCurrentRanks = currentRanks.size();
         PIPE_WRITE(childId, tempCurrentRanks);