[SYCL] Fix Coverity hits

- Make Managed's move assignment safe for self-assignment
- Move instead of copy in GetCapabilitiesIntersectionSet

Author: sergey-semenov

sycl/source/detail/adapter_impl.hpp

@@ -264,11 +264,12 @@ template <typename URResource> class Managed {
   }
   Managed &operator=(const Managed &) = delete;
   Managed &operator=(Managed &&Other) {
+    URResource Temp = Other.R;
+    Other.R = nullptr;
     if (R)
       Adapter->call<Release>(R);
+    R = Temp;
 
-    R = Other.R;
-    Other.R = nullptr;
     Adapter = Other.Adapter;
     return *this;
   }

sycl/source/detail/context_impl.hpp

@@ -348,7 +348,7 @@ void GetCapabilitiesIntersectionSet(devices_range Devices,
         CapabilityList.begin(), CapabilityList.end(),
         DeviceCapabilities.begin(), DeviceCapabilities.end(),
         std::inserter(NewCapabilityList, NewCapabilityList.begin()));
-    CapabilityList = NewCapabilityList;
+    CapabilityList = std::move(NewCapabilityList);
   }
   CapabilityList.shrink_to_fit();
 }