Allow DML EP to be used with any CPU EP (microsoft#25664)

### Description
<!-- Describe your changes. -->
Relax restriction on DML EP so other CPU based EPs can be used. 


### Motivation and Context
<!-- - Why is this change required? What problem does it solve?
- If it fixes an open issue, please link to the issue here. -->
microsoft#25504

Author: skottmckay

include/onnxruntime/core/framework/execution_provider.h

@@ -179,7 +179,12 @@ class IExecutionProvider {
   /**
      Get the device id of current execution provider
   */
-  virtual int GetDeviceId() const { return default_device_.Id(); };
+  virtual int GetDeviceId() const { return default_device_.Id(); }
+
+  /**
+   * Get the OrtDevice the execution provider was registered with.
+   */
+  const OrtDevice& GetDevice() const { return default_device_; }
 
   /**
      Get execution provider's configuration options.

onnxruntime/core/session/inference_session.cc

@@ -1984,13 +1984,15 @@ static void ResolveMemoryPatternFlags(SessionState& session_state) {
 // For now, this function only checks for invalid combination of DML EP with other EPs.
 // TODO: extend this function to check for other invalid combinations of EPs.
 common::Status InferenceSession::HasInvalidCombinationOfExecutionProviders() const {
-  // DML EP is only allowed with CPU EP
+  // DML EP is not allowed with other GPU or NPU EPs.
+  // historical reason for this is unknown. relaxing the limit that it must only be used with the CPU EP to support
+  // scenarios where alternative EPs are CPU based (e.g. openvino).
   bool has_dml_ep = execution_providers_.Get(kDmlExecutionProvider) != nullptr;
   if (has_dml_ep) {
-    const auto& ep_list = execution_providers_.GetIds();
-    for (const auto& ep : ep_list) {
-      if (ep == kDmlExecutionProvider || ep == kCpuExecutionProvider) continue;
-      return common::Status(common::ONNXRUNTIME, common::INVALID_ARGUMENT, "DML EP can be used with only CPU EP.");
+    for (const auto& ep : execution_providers_) {
+      if (ep->Type() != kDmlExecutionProvider && ep->GetDevice().Type() != OrtDevice::CPU) {
+        return common::Status(common::ONNXRUNTIME, common::INVALID_ARGUMENT, "DML EP can only be used with CPU EPs.");
+      }
     }
   }
   return Status::OK();