speedtest-netperf: new package to measure network performance

speedtest-netperf: new package to measure network performance

The speedtest-netperf.sh script measures the network throughput while
monitoring latency under load and capturing key CPU usage and frequency
statistics. The script can emulate a web-based speed test by downloading
and then uploading from an internet server, or perform simultaneous
download and upload to mimic the stress of the FLENT test program.

It simplifies tasks such as validating ISP provisioned speeds or setting
up and fine-tuning SQM, directly on the router. The CPU usage details
can also help determine if the demands of SQM, routing and other tasks
such as the test itself are exhausting the device's CPUs.

This script leverages earlier scripts from the CeroWrt project used for
bufferbloat mitigation, betterspeedtest.sh and netperfrunner.sh. They are
used with the permission of the author, Rich Brown.

Signed-off-by: Tony Ambardar <itugrok@yahoo.com>
(cherry-picked from 463590e2bcf94e09890f7ba98e910ff58090e29b)