iPerf2 for Android

The goals include maintaining an active iperf 2 code base (code originated from iperf 2.0.5), preserving interoperability with iperf 2.0.5 clients and servers, preserving the output for scripts (new enhanced output requires -e), adopt known 2.0.x bug fixes, maintain broad platform support, as well as add some essential feature enhancements mostly driven by WiFi testing needs. Also added python code to centralize test control.

For more info : https://sourceforge.net/projects/iperf2/

Recent changes:
Support Android 14.
Fix external storage permission.
Update Iperf version to 2.2.1.