Part of #7886.
This PR conditionally installs mock in `apache/setup.py` based on setuptools version and python version, when possible. It then updates `apache` tests to use `unittest.mock` when `mock` isn't available.
* Conditionally install mock in apache
* error out on newer python and older setuptools
* error when trying to build wheels with old setuptools
* use unittest.mock when third-party mock isn't available in apache, with no cover and type ignore
* Load apacheconfig dependency, gate behind flag
* Bump apacheconfig dependency to latest version and install dev version of apache for coverage tests
* Move augeasnode_test tests to more generic parsernode_test
* Revert "Move augeasnode_test tests to more generic parsernode_test"
This reverts commit 6bb986ef78.
* Mock AugeasNode into DualNode's place, and run augeasnode tests exclusively on AugeasNode
* Don't calculate coverage for skeleton functions
* clean up helper function in augeasnode_test
