Improved test_main

[adamchalmers]

The CLI tests in test_main were annoying so here's some problems and fixes:

• Before this PR, a single failing test would stop all the other tests. So you'd have to keep rerunning to fix a lot of little failures.
  • Fix: Now instead it'll run all tests, collecting failures and printing them all at the end.
• Before this PR, if the 39th test failed, rerunning the CLI tests would make you run all the preceding 38 tests before failing. Which made rerunning to see if you fixed the test quite slow.
  • Fix: Allow ZOO_CLI_TEST_NAME var. If it's set, only tests whose name contain that value will be run. This means if you know

I tried to just split the test up into many tests, which would have let us use nextest to get all these features. But unfortunately I wasn't able to get it to work. Here's my attempt.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.23%. Comparing base (653fc32) to head (7930cf5).
Report is 2 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1305       +/-   ##
===========================================
- Coverage   74.82%   64.23%   -10.59%     
===========================================
  Files          37       37               
  Lines        5629     5629               
===========================================
- Hits         4212     3616      -596     
- Misses       1417     2013      +596     

Flag	Coverage Δ
unittests	64.23% <ø> (-10.59%)	⬇️

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