[FlightRPC][C++][Python] Header-based auth in servers

Add support for a middleware that executes header-based authorization to C++ and Python servers.

The design should be such that a Flight server can validate incoming headers then generate a peer identity and write outgoing headers in response to the request.

Provide an implementation using Basic authentication.

**Reporter**: [James Duong](https://issues.apache.org/jira/browse/ARROW-10488) / @jduo

_{**Note**: *This issue was originally created as [ARROW-10488](https://issues.apache.org/jira/browse/ARROW-10488). Please see the [migration documentation](https://github.com/apache/arrow/issues/14542) for further details.*}

未指定任何檔案或測試。首先定位 C++ 和 Python Flight 伺服器中介軟體的進入點，然後追蹤傳入和傳出標頭以及對等端身分的處理方式。完成的標準是兩個伺服器都支援標頭驗證、對等端身分產生、回應標頭以及 Basic authentication 實作。

由索引模型根據 Issue 內容生成。