[Flight] Find client address from ArrowFlightServer

We want a cookbook entry for Python/C++/Java describing how to get Arrow Flight Server client's address.
* [Java](https://stackoverflow.com/a/36140002/262727)
* [Python](https://arrow.apache.org/docs/python/generated/pyarrow.flight.ServerCallContext.html#pyarrow.flight.ServerCallContext.peer)
* [C++](https://arrow.apache.org/docs/cpp/api/flight.html#_CPPv4NK5arrow6flight17ServerCallContext4peerEv)

Start by reviewing the linked Java, Python, and C++ references for ServerCallContext.peer and inspect the cookbook's existing Flight entries to find the appropriate location and format. Add a cookbook example covering how to obtain the client's address in all three languages, with the documented result matching each API's behavior.

Written by the indexing model from the issue text.