By Atharva Singh and Arasu Kannagi Basil (Reuters) - Cybersecurity firm Netskope commanded an $8.79 billion valuation as its shares jumped 21% in their Nasdaq debut on Thursday, adding to a string of successful tech IPOs this year. The Santa Clara, California-based company's shares opened at $23 apiece, well above the $19 offer price. Netskope raised $908.2 million in its IPO by selling 47.8 million shares at the top end of its bumped-up range of $17 to $19 apiece. The U.S. IPO market is enjoying its st ...