update k4a c++ functions to support function chaining #1514

void set_timestamp(std::chrono::microseconds timestamp);  // old
k4a::image& set_timestamp(std::chrono::microseconds timestamp);  // new

void set_depth_image(const image &depth_image);  // old
k4a::capture& set_depth_image(const image &depth_image);  // new

// this enables function chaining...
k4a::capture capture;
k4a::image image;
image.set_timestamp(1234).set_exposure_time(7500);
capture.set_depth_image(image).set_color_image(image).set_temperature_c(30.2);

// existing SDK 1.4.1 code
void set_temperature_c(float temperature_c) noexcept
{
    k4a_capture_set_temperature_c(m_handle, temperature_c);
}

// new code
k4a::image& set_temperature_c(float temperature_c) noexcept
{
    k4a_capture_set_temperature_c(m_handle, temperature_c);
    return *this;
}