Create a `tracing` feature about foundationdb-rs

[KrzysFR]

Nobody can say no to a nicely formatted ASCII chart!

I would have have been able to develop and debug all the fdb layers I worked on without this tool!

It's not perfect: what is missing is being able to merge multiple traces together side by side, when you need to understand the interplay between multiple concurrent transactions.

Feel free to reuse the formatting code if you need! It's a bit of a mess with C# string.Format(...) but should be somewhat straightforward to replicate.

[PierreZ]

It's not perfect: what is missing is being able to merge multiple traces together side by side, when you need to understand the interplay between multiple concurrent transactions.

This will be possible with fdb-7.0 and their tracing feature