feat: replace single bit range constraints with basic bool gates (Azt…

…ecProtocol#4164)

This PR pulls the optimisation made in
noir-lang/noir#3234 across into the backend.

barretenberg/cpp/src/barretenberg/proof_system/circuit_builder/ultra_circuit_builder.hpp

@@ -779,7 +779,9 @@ class UltraCircuitBuilder_ : public CircuitBuilderBase<typename Arithmetization:
                                      std::string const msg = "create_new_range_constraint");
     void create_range_constraint(const uint32_t variable_index, const size_t num_bits, std::string const& msg)
     {
-        if (num_bits <= DEFAULT_PLOOKUP_RANGE_BITNUM) {
+        if (num_bits == 1) {
+            create_bool_gate(variable_index);
+        } else if (num_bits <= DEFAULT_PLOOKUP_RANGE_BITNUM) {
             /**
              * N.B. if `variable_index` is not used in any arithmetic constraints, this will create an unsatisfiable
              *      circuit!