These are fixes related to tests that ideally should have been included in !30 (merged)

Three main things, over multiple commits each:

• Fix parts of tests framework: zc.recipe.egg tests previously not included by default, missing imports, incomplete renames, workaround for a recent setuptools quirk...
• Adapt to setuptools>=65.6.0 switching to standard logging lib and logging on root: this changed outputs, breaking tests (most of which are output-based).
• Make tests invariant from test environment: some tests succeeded locally with python dev.py + bin/test but failed in our test suites, because some dependencies were installed differently, causing differences from expected outputs.

Regarding merging: it seems judicious to rewrite history since 3.0.1 to immediately apply fixups and reorder commits in a way that presents our patches over 3.0.1 cohesively, instead of leaving this as work for later rebases or merging upstream, that will accumulate and makes such rebases harder. This rewrite has already been done in parallel branch rebase/fix-buildout-logs-for-recent-setuptools, which has the exact same working tree but a rewritten history since 3.0.1.

This MR would then be for exposition purposes - after merging, we would reset slapos.buildout!master to rebase/fix-buildout-logs-for-recent-setuptools to keep a cohesive history.