Depends on D5027
Linear task: https://linear.app/comm/issue/ENG-1727/catch-stdexception-in-base-reactors
We started using rust, and we use functions that return `Result`. That `Result` is then converted into a `std::exception` in c++ when it returns `Err`. All over the place in the reactors we handle `std::runtime_errors` but we should go higher in the [hierarchy](https://stdcxx.apache.org/doc/stdlibug/18-2.html) and catch std::exceptions.
Here, I removed rethrowing in add attachments utility as it is caught in the base reactors (earlier in this stack).