Behind a massive IT failure that grounded flights, upended markets and disrupted corporations around the world is one cybersecurity company: CrowdStrike Holdings Inc.Known as a dominant supplier of software that protects businesses from ransomware attacks, CrowdStrike was thrust into the spotlight on Friday as it struggled to fix a faulty patch that led to cascading, system-wide failures, paralyzing the operations of clients ranging from banks to global retail giants to health-care systems....