Branch, the deep-linking startup backed by Andy Rubin’s Playground Ventures, will enter the unicorn club with an upcoming funding round. The four-year-old company, which helps brands create links between websites and mobile apps, has authorized the sale of $129 million in Series D shares, according to sources and confirmed by PitchBook, which tracks venture capital deals. The infusion of capital values the company at roughly $1 billion. In an e-mail this morning, Branch CEO A