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GH-40690: [C#][FlightRPC] Add do_exchange csharp implementation (#40691)

### Rationale for this change

This is a draft implementation of DoExchange. A simple usage demo is in FlightTests.cs and TestFlightServer.cs.
I've tried to share the implementation with DoGet/DoPut as much as possible.

### What changes are included in this PR?

- FlightServer.cs and related FlightServerImplementation.cs
- FlightClient.cs with (new) FlightRecordBatchExchangeCall.cs wrapper call.

### Are these changes tested?

Yes, tests are added in FlightTest.cs and TestFlightServer.cs
I've tested locally with the C++ implementation.

### Are there any user-facing changes?

No and the DoExchange documentation is already present

* GitHub Issue: #40690

Lead-authored-by: Marco Malagoli <mmalagoli@board.com>
Co-authored-by: qmmk <47608571+qmmk@users.noreply.github.com>
Signed-off-by: Curt Hagenlocher <curt@hagenlocher.org>