Refactoring of log_point_cloud2

Hi @roym899, 
Are you open for a [PR](https://github.com/rerun-io/cpp-example-ros2-bridge/pull/14), which addresses some problems in: `log_point_cloud2`? 

btw. I noticed that `.clang-format` file is based on Google Style, but existing code rather follows Python style. (snake_case, leading underscore for private members). Is it intentional? 