A memorial service has been held in Kyiv for the victims of a Russian missile strike on a children’s hospital on Monday. A chamber orchestra played in the rubble of the building in Kyiv on Friday as part of the commemoration service. Ukraine’s largest medical facility for children was caring for 627 patients at the time of the attack, which killed at least 44 people. Dozens of children already battling life-threatening diseases were also injured. Oksana Halak only learned about her 2-year-old son Dmytro’s diagnosis — acute lymphoblastic leukemia — at the beginning of June. She immediately deci…