Moved mscclpp_ncclGetUniqueId call into ncclCommInitRankFunc (#1332)

* Moved call to `mscclpp_ncclGetUniqueId` into `ncclCommInitRankFunc` to avoid setting up transport early in environments where MSCCL++ isn't valid.

* Checking `mscclEnabled` for the process and the topology to gate MSCCL++.

* Allowed `mscclForceEnable` to enable MSCCL++.

src/misc/msccl/msccl_lifecycle.cc

@@ -84,6 +84,12 @@ static bool mscclCommCompatible(ncclComm_t comm) {
   return true;
 }
 
+#ifdef ENABLE_MSCCLPP
+bool mscclppCommCompatible(ncclComm_t comm) {
+  return mscclCommCompatible(comm);
+}
+#endif
+
 const char *mscclFuncNames[] = {
             "mscclFuncReduce",
             "mscclFuncBroadcast",