Textures: fixed a building issue when ImTextureID is defined as a struct.

+ Added CI for this case.

imgui_internal.h

@@ -335,7 +335,6 @@ extern IMGUI_API ImGuiContext* GImGui;  // Current implicit context pointer
 #define IM_PRIu64   "llu"
 #define IM_PRIX64   "llX"
 #endif
-#define IM_TEXTUREID_TO_U64(_TEXID) ((ImU64)(intptr_t)(_TEXID))
 
 //-----------------------------------------------------------------------------
 // [SECTION] Generic helpers
@@ -3697,6 +3696,7 @@ namespace ImGui
     IMGUI_API bool          DebugBreakButton(const char* label, const char* description_of_location);
     IMGUI_API void          DebugBreakButtonTooltip(bool keyboard_only, const char* description_of_location);
     IMGUI_API void          ShowFontAtlas(ImFontAtlas* atlas);
+    IMGUI_API ImU64         DebugTextureIDToU64(ImTextureID tex_id);
     IMGUI_API void          DebugHookIdInfo(ImGuiID id, ImGuiDataType data_type, const void* data_id, const void* data_id_end);
     IMGUI_API void          DebugNodeColumns(ImGuiOldColumns* columns);
     IMGUI_API void          DebugNodeDrawList(ImGuiWindow* window, ImGuiViewportP* viewport, const ImDrawList* draw_list, const char* label);