GPU allocation for CPX Unit Tests using PCI bus id (#1403)

* mapping devices wrt pci

* Gpu allocation by using pci mapping

* Passing gpuPriorityOrder in as an argument rather than making the functions non-static.

* Removing redundant testBed instance calling

test/NonBlockingTests.cpp

@@ -34,7 +34,8 @@ namespace RcclUnitTesting
     {
       int const numProcesses = isMultiProcess ? totalRanks : 1;
       // Initialize communicators in non-blocking mode
-      testBed.InitComms(TestBed::GetDeviceIdsList(numProcesses, totalRanks), 1, 1, 1, useBlocking);
+      const std::vector<int>& gpuPriorityOrder = testBed.ev.GetGpuPriorityOrder();
+      testBed.InitComms(TestBed::GetDeviceIdsList(numProcesses, totalRanks, gpuPriorityOrder), 1, 1, 1, useBlocking);
 
       // Loop over various collective functions
       for (auto funcType : funcTypes)