“Whether, in determining whether a claim is directed to patent-eligible subject matter under 35 U.S.C. §101, the claim must be ‘considered in light of the specification,’ as held in Enfish, LLC v. Microsoft Corp., 822 F.3d 1327, 1335 (Fed. Cir. 2016), or whether the court’s analysis is confined to considering what is ‘recited in the claims’ themselves, as the panel majority held here.”