Add basic arithmetization class.

cpp/src/barretenberg/proof_system/arithmetization/arithmetization.hpp

@@ -0,0 +1,25 @@
+#include <cstddef>
+
+namespace arithmetization {
+
+template <size_t _num_wires, size_t _num_gates> struct Arithmetization {
+    static constexpr size_t num_wires = 3;
+    static constexpr size_t num_selectors = 7;
+    // Note: For even greater modularity, in eace instantiation we could specify a list of components here, where a
+    // component is a meaningful collection of functions for creating gates, as in:
+    //
+    // struct Component {
+    //     using Arithmetic = component::Arithmetic3Wires;
+    //     using RangeConstraints = component::Base4Accumulators or component::GenPerm or...
+    //     using LooupTables = component::Plookup4Wire or component::CQ8Wire or...
+    //     ...
+    // };
+    //
+    // We should only do this if it becomes necessary or convenient, as might happen when implementing certain execution
+    // trace layout optimizations.
+};
+
+using Standard = Arithmetization<3, 7>;
+using Turbo = Arithmetization<4, 11>;
+
+} // namespace arithmetization