refactor(avm): remove some codegen bloat (#11418)

TL;DR: Removes bloat, old and new witgen are still proving. Please review without nitpicking I recommend just merging if CI passes.

More detail:
* Removes explicit column names, they now get generated via the macro.
* Remove as_vector, replaced uses with get_column (and commented out some other uses).

I also added, in vm2, nice per-namespace stats:

```
Column sizes per namespace:
  precomputed: 2097152 (~2^21)
  execution: 6 (~2^3)
  alu: 1 (~2^0)
  lookup: 196608 (~2^18)
  perm: 6 (~2^3)
```

It autoupdates without us having to add columns manually.

barretenberg/cpp/src/barretenberg/vm/avm/generated/circuit_builder.cpp

@@ -1,5 +1,6 @@
 // AUTOGENERATED FILE
 #include "circuit_builder.hpp"
+#include "columns.hpp"
 
 #include <mutex>
 #include <set>
@@ -27,7 +28,7 @@ AvmCircuitBuilder::ProverPolynomials AvmCircuitBuilder::compute_polynomials() co
     // We create a mapping between the polynomial index and the corresponding column index when row
     // is expressed as a vector, i.e., column of the trace matrix.
     std::unordered_map<std::string, size_t> names_to_col_idx;
-    const auto names = Row::names();
+    const auto names = COLUMN_NAMES;
     for (size_t i = 0; i < names.size(); i++) {
         names_to_col_idx[names[i]] = i;
     }
@@ -63,9 +64,9 @@ AvmCircuitBuilder::ProverPolynomials AvmCircuitBuilder::compute_polynomials() co
                        // Non-parallel version takes 0.5 second for a trace size of 200k rows.
                        // A parallel version might be considered in the future.
                        for (size_t i = 0; i < num_rows; i++) {
-                           const auto row = rows[i].as_vector();
+                           const auto& row = rows[i];
                            for (size_t col = 0; col < Row::SIZE; col++) {
-                               if (!row[col].is_zero()) {
+                               if (!row.get_column(static_cast<ColumnAndShifts>(col)).is_zero()) {
                                    col_nonzero_size[col] = i + 1;
                                }
                            }

barretenberg/cpp/src/barretenberg/vm/avm/generated/columns.hpp

@@ -3,6 +3,8 @@
 #include <array>
 #include <optional>
 
+#include "barretenberg/common/std_string.hpp"
+
 namespace bb::avm {
 
 // The entities that will be used in the flavor.
@@ -33,4 +35,12 @@ constexpr auto TO_BE_SHIFTED_COLUMNS_ARRAY = []() { return std::array{ AVM_TO_BE
 constexpr auto SHIFTED_COLUMNS_ARRAY = []() { return std::array{ AVM_SHIFTED_COLUMNS }; }();
 static_assert(TO_BE_SHIFTED_COLUMNS_ARRAY.size() == SHIFTED_COLUMNS_ARRAY.size());
 
+// Two layers are needed to properly expand the macro. Don't ask why.
+#define VARARGS_TO_STRING(...) #__VA_ARGS__
+#define UNPACK_TO_STRING(...) VARARGS_TO_STRING(__VA_ARGS__)
+inline const std::vector<std::string>& COLUMN_NAMES = []() {
+    static auto vec = detail::split_and_trim(UNPACK_TO_STRING(AVM_ALL_ENTITIES), ',');
+    return vec;
+}();
+
 } // namespace bb::avm