Support for `resize` [perhaps also `capacity` and `reserve`] for cista::generic_string/basic_string about cista HOT 2 OPEN

struct InputTextCallback_Meta
{
    madX::Meta::String* string_;
    ImGuiInputTextCallback chain_callback_;
    void* chain_user_data_;
};

static int Meta_InputTextCallback(ImGuiInputTextCallbackData* data)
{
    InputTextCallback_Meta* user_data = (InputTextCallback_Meta*)data->UserData;
    if (data->EventFlag == ImGuiInputTextFlags_CallbackResize)
    {
        madX::Meta::String* string = user_data->string_;
        IM_ASSERT(data->Buf == string->data());
        
        string->move_from(madX::Meta::String("", data->BufTextLen < madX::Meta::StringShortLength ? madX::Meta::StringShortLength : data->BufTextLen));
        data->Buf = string->data();
    }
    else if (user_data->chain_callback_)
    {
        data->UserData = user_data->chain_user_data_;
        return user_data->chain_callback_(data);
    }
    return 0;
}

bool ImGui::InputTextWithHint(const char* label, const char* hint, madX::Meta::String* string, ImGuiInputTextFlags flags, ImGuiInputTextCallback callback, void* user_data)
{
    IM_ASSERT(string);
    IM_ASSERT((flags & ImGuiInputTextFlags_CallbackResize) == 0);
    flags |= ImGuiInputTextFlags_CallbackResize;
   
    InputTextCallback_Meta meta
    {
        string,
        callback,
        user_data
    };

    return InputTextWithHint
    (
        label,
        hint,
        string->data(),
        string->size() + 1,
        flags,
        Meta_InputTextCallback,
        &meta
    );
}