Misc: Avoid stb_textedit.h reincluding string.h while in a namespace. (#6653, #4791)

imgui_widgets.cpp

@@ -3812,6 +3812,7 @@ static bool STB_TEXTEDIT_INSERTCHARS(ImGuiInputTextState* obj, int pos, const Im
 #define STB_TEXTEDIT_K_SHIFT        0x400000
 
 #define STB_TEXTEDIT_IMPLEMENTATION
+#define STB_TEXTEDIT_memmove memmove
 #include "imstb_textedit.h"
 
 // stb_textedit internally allows for a single undo record to do addition and deletion, but somehow, calling