By Jody Godoy SAN FRANCISCO (Reuters) -Elon Musk, Tesla Inc’s chief executive, took the stand on Friday in a jury trial over his 2018 Twitter post that he had “funding secured” to take the electric carmaker private, which shareholders allege cost them millions in trading losses. The class action trial in San Francisco federal court resumed with investor Timothy Fries telling the jury how he lost $5,000 buying Tesla stock after Musk sent the tweet at the center of the lawsuit. Musk, known for combative testimony, is expected to address why he has insisted he had Saudi investor backing to take T…