Two years ago, Jacob Helberg, a little-known tech industry adviser, convened a dinner between lawmakers and a small group of Silicon Valley insiders on Washington’s Embassy Row. The informal supper club, which would eventually receive funding from billionaire investor Peter Thiel’s venture firm, was not distinctive for its wealth or clout — the people involved had plenty of both — but for its members’ eagerness to eschew the industry’s long-held ideals of boundaryless technology for an alternative vision rooted in American nationalism and an anti-China might.