This applies the "whitelist" => "include" changes to all the core
phpunit_coverage_info occurrences, so core won't emit any deprecation
warning (see previous commit).
At the same time, modified a bunch of comments in coverage files
to be more readable/understandable.
All the setup/teardown/pre/post/conditions template methods
now are required to return void. This was warned with phpunit 7
and now is enforced.
At the same time, fix a few wrong function names,
provider data and param types, return statements...
