message: Allow users to skip bytes while deserializing
diff: @@ -72,6 +72,13 @@ public:
  /// Returns how many bytes are still available to read.
  size_t remaining() const;
  + /// Jumps `num_bytes` forward.
  + /// @pre `num_bytes <= remaining()`
  + void skip(size_t num_bytes) {
  + current_ += num_bytes;
  + }
  +
  +
  protected:
  error apply_impl(int8_t&) override;
  