By Stephanie Kelly and Scott DiSavino NEW YORK (Reuters) -Energy company executives at a conference on the global transition insisted on Tuesday that fossil fuels, especially natural gas, are still needed at a time when global markets grapple with tight energy supplies and skyrocketing prices. Oil and gas supplies have become constricted in many countries since Russia invaded Ukraine on Feb. 24, prompting sanctions on Russia’s energy. Governments worldwide have shifted their focus from sustainability and the energy transition to deep concerns about a global supply crunch and demands for more o…