message: revert map and set to string_t
diff: namespace duckdb {
  struct StringHash {
  - std::size_t operator()(const string_t &k) const {
  - return Hash(k.GetDataUnsafe(), k.GetSize());
  + std::size_t operator()(const string &k) const {
  + return Hash(k.c_str(), k.size());
  }
  };
  struct StringCompare {
  - bool operator()(const string_t &lhs, const string_t &rhs) const {
  - return StringComparisonOperators::EqualsOrNot<false>(lhs, rhs);
  + bool operator()(const string &lhs, const string &rhs) const {
  + return lhs == rhs;
  }
  };
  @@ -177,7 +177,7 @@ struct DictionaryCompressionCompressState : public DictionaryCompressionState {
  data_ptr_t current_end_ptr;
  // Buffers and map for current segment
  - std::unordered_map<string_t, uint32_t, StringHash, StringCompare> current_string_map;
  + std::unordered_map<string, uint32_t, StringHash, StringCompare> current_string_map;
  std::vector<uint32_t> index_buffer;
  std::vector<uint32_t> selection_buffer;
  @@ -197,7 +197,7 @@ struct DictionaryCompressionCompressState : public DictionaryCompressionState {
  }
  bool LookupString(string_t str) override {
  - auto search = current_string_map.find(str);
  + auto search = current_string_map.find(str.GetString());
  auto has_result = search != current_string_map.end();
  if (has_result) {
  @@ -219,7 +219,7 @@ struct DictionaryCompressionCompressState : public DictionaryCompressionState {
  // Update buffers and map
  index_buffer.push_back(current_dictionary.size);
  selection_buffer.push_back(index_buffer.size() - 1);
  - current_string_map.insert({str, index_buffer.size() - 1});
  + current_string_map.insert({str.GetString(), index_buffer.size() - 1});
  DictionaryCompressionStorage::SetDictionary(*current_segment, *current_handle, current_dictionary);
  current_width = next_width;
  @@ -328,19 +328,19 @@ struct DictionaryCompressionAnalyzeState : public AnalyzeState, DictionaryCompre
  idx_t current_tuple_count;
  idx_t current_unique_count;
  size_t current_dict_size;
  - std::unordered_set<string_t, StringHash, StringCompare> current_set;
  + std::unordered_set<string, StringHash, StringCompare> current_set;
  bitpacking_width_t current_width;
  bitpacking_width_t next_width;
  bool LookupString(string_t str) override {
  - return current_set.count(str);
  + return current_set.count(str.GetString());
  }
  void AddNewString(string_t str) override {
  current_tuple_count++;
  current_unique_count++;
  current_dict_size += str.GetSize();
  - current_set.insert(str);
  + current_set.insert(str.GetString());
  current_width = next_width;
  }
  