bug 1399639: Refactor ExtractCodeSampleTests
bug 1399639: Refactor ExtractCodeSampleTests

Convert ExtractCodeSampleTests to pytest standards, include with other
Extractor.code_sample tests.

jwhitlock/kuma,Elchi3/kuma,SphinxKnight/kuma,jwhitlock/kuma,mozilla/kuma,a2sheppy/kuma,mozilla/kuma,mozilla/kuma,SphinxKnight/kuma,SphinxKnight/kuma,escattone/kuma,SphinxKnight/kuma,escattone/kuma,Elchi3/kuma,Elchi3/kuma,jwhitlock/kuma,Elchi3/kuma,a2sheppy/kuma,Elchi3/kuma,a2sheppy/kuma,escattone/kuma,SphinxKnight/kuma,a2sheppy/kuma,jwhitlock/kuma,mozilla/kuma,a2sheppy/kuma,SphinxKnight/kuma,mozilla/kuma,jwhitlock/kuma