Pester v5.2.0 added the ability to natively run just the discovery phase
of a test suite, so we refactor Measure-Koan to utilize this and save
doing a lot of manual work.

This also obsoletes the private Measure-KoanTestBlock command that
previously supported Measure-Koan. Pester automatically does that
calculation on its own before presenting the discovery results. This
command has been removed as a result.

In some cases it looks like Pester can fail to publish if there are too
many versions of Pester available. Prevent this by checking the version
we actually need and publishing just that version when doing a publish
to the filesystem.

Also set the initially installed version of pester to the correct
version based on the current required version specified by PSKoans
itself, instead of having to update the environment-setup.yml each time.

This issue was fixed in 5.2.1 of Pester