Can replace the following SlapTool calls:
* softwareReleaseError
* availableSoftwareRelease
* buildingSoftwareRelease
* destroyedSoftwareRelease

See merge request !455

See merge request !478

See merge request !495

This is no longer guessed on Zope4

this way we can just assert the full page content

this does not depend on the details of the URL

See merge request !493

   .. on consistency table

See merge request nexedi/slapos.core!489

See merge request nexedi/slapos.core!490

Adding the whole top-level available IPv6 range to the local table
conflicts with tun/tap usage. Instead, add only the IPv6 subranges
actually allocated to a partition.