Debug Tools: Rename ShowIdStackToolWindow() -> ShowIDStackToolWindow(). (#4631)

Some tool undid or didn't queue a chunk? Amend c21278e.
diff --git a/imgui_internal.h b/imgui_internal.h
index ed9365b..73b3f2e 100644
--- a/imgui_internal.h
+++ b/imgui_internal.h
@@ -2149,7 +2149,7 @@
     ImU8                    DebugItemPickerMouseButton;
     ImGuiID                 DebugItemPickerBreakId;             // Will call IM_DEBUG_BREAK() when encountering this ID
     ImGuiMetricsConfig      DebugMetricsConfig;
-    ImGuiIDStackTool        DebugIdStackTool;
+    ImGuiIDStackTool        DebugIDStackTool;
     ImGuiDebugAllocInfo     DebugAllocInfo;
 
     // Misc