[docker-ptf]PTF adds xmlrunner for xunit report

[richardyu-ms]

Why I did it

add xmlrunner to generate the test report in xunit format

How I did it

add xmlrunner to generate the test report in xunit format

How to verify it

built the ptf docker and check the function with test cases

• vxlan/test_vxlan_decap.py
• local test case for sai testing

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106

Description for the changelog

A picture of a cute animal (not mandatory but encouraged)

[wangxin]

The xmlrunner package is pretty old. Not sure if it supports python3 well. We need to consider python3 support while adding packages. Is the unittest-xml-reporting package a better option?

Reference: https://github.com/xmlrunner/unittest-xml-reporting

[lguohan]

@wangxin , why not using pytest report? can we converge on using one report same as sonic-mgmt?

[wangxin]

@guohan, talked with @richardyu-ms, each SAI PTF script has many test cases. However, for a pytest case running the PTF script, it will only report single result based on pass or fail of the PTF script. It would be better for the PTF script to generate a junit xml result with more fine grained results. The junit xml result can be copied back to sonic-mgmt. Then we can take advantage of the existing tools to process the PTF script junit XML result files to generate better test reports.