Show progress dialog during startup (#9255)

* Show progress dialog during startup for selection enumeration that can take a long time.

* Updated with better code organization and a timer to ensure the progress dialog does not appear in most cases.

* Update based on PR feedback

* Change progress dialog delay from 1500ms to 2500ms

* Move progress dialog invocation off the main UI thread

Co-authored-by: Chris Davis (EDGE) <chrdavis@microsoft.com>

src/modules/powerrename/lib/PowerRenameEnum.h

@@ -0,0 +1,34 @@
+#pragma once
+#include "pch.h"
+#include "PowerRenameInterfaces.h"
+#include <vector>
+#include "srwlock.h"
+
+class CPowerRenameEnum :
+    public IPowerRenameEnum
+{
+public:
+    // IUnknown
+    IFACEMETHODIMP QueryInterface(_In_ REFIID iid, _Outptr_ void** resultInterface);
+    IFACEMETHODIMP_(ULONG) AddRef();
+    IFACEMETHODIMP_(ULONG) Release();
+
+    // ISmartRenameEnum
+    IFACEMETHODIMP Start();
+    IFACEMETHODIMP Cancel();
+
+public:
+    static HRESULT s_CreateInstance(_In_ IUnknown* pdo, _In_ IPowerRenameManager* pManager, _In_ REFIID iid, _Outptr_ void** resultInterface);
+
+protected:
+    CPowerRenameEnum();
+    virtual ~CPowerRenameEnum();
+
+    HRESULT _Init(_In_ IUnknown* pdo, _In_ IPowerRenameManager* pManager);
+    HRESULT _ParseEnumItems(_In_ IEnumShellItems* pesi, _In_ int depth = 0);
+
+    CComPtr<IPowerRenameManager> m_spsrm;
+    CComPtr<IUnknown> m_spdo;
+    bool m_canceled = false;
+    long m_refCount = 0;
+};