Add tests for `--recovery` mode

[baileythegreen]

Recovery mode currently has no tests, which means any code inside blocks activated only in recovery mode are never tested;

One example here: https://github.com/widdowquinn/pyani/pull/355/commits/e6c606ad082c966fb89a9e26b25613406448285c

The relevant code occurs inside files like subcmd_anim.py, which historically do not have any monkeypatched or mocked tests, except for concordance checks.

I propose a test_recovery.py that contains all of the --recovery mode tests, similar in style to test_concordance.py.

Python Version:

v3