Also:
1. Support coverage builds.
2. Add an integration test for coverage builds and reports.
3. Refactor docker code so that there is less duplication in getting arguments for docker run, in particular when handling container (production) vs no container (testing).
4. Rename coverage.py to get_coverage_report.
5. Add tests for untested functions in docker.py
6. Add a test for get_fuzz_target_runner.
Move entrypoints for CIFuzz to cifuzz.
This allows us to reduce some complexity by getting rid of
an unnecessary copy in docker and a hack to making importing work.
jonathanmetzman