Implement Error::Source for ArrowError and FlightError

[alamb]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.
In IOx (and in DataFusion) we often want to know what the root cause of an error is (e.g was it a bug or was it a resources exhausted). ArrowError can wrap other errors with Arrow::External (and DataFusion has something similar) but there is no easy way to get at the source of the error to walk the chain without knowing all the possible types that may be present

I believe this is what https://doc.rust-lang.org/std/error/trait.Error.html#method.source is for

I would like to be able to write something like this to walk the chain

        let mut root_error: &dyn Error = &e3;
        loop {
            match root_error.source() {
                // walk the next level
                Some(source) => root_error = source,
                // at root (as much as we know)
                None => break,
            }
        }

However, ArrowError does not implement source yet

Of course, all the errors in the chain need to implement this

Describe the solution you'd like
For ArrowError / FlightError that wrap other errors, implement Error::source()

Describe alternatives you've considered
See https://github.com/apache/arrow-datafusion/blob/dde23efed94704044822bcefe49c0af7f9260088/datafusion/common/src/error.rs#L361-L439 for what we need to do now in datafusion 🤮

cc @crepererum

Additional context

[crepererum]

I think we should replace the find_root method in DataFusion with this mechanism as well and embrace the standard 💪

[alamb]

I think we should replace the find_root method in DataFusion with this mechanism as well and embrace the standard 💪

On it!

[alamb]

Follow on ticket in datafusion: apache/datafusion#4991

[tustvold]

label_issue.py automatically added labels {'arrow'} from #3567

[tustvold]

label_issue.py automatically added labels {'arrow-flight'} from #3567