Fix installation of slapos.toolbox

Since f3613b91 (version up slapos.toolbox 0.110, 2020-08-21) slapos.toolbox needs lzma, which should always be installed with slapos component, because letting buildout install the egg from pypi would build against system libzma library (or fail if not present).
This introduce `*-dependencies` sections for eggs that have some dependencies that needs to be installed by slapos and use it, especially in section which install eggs from git for testing.

See merge request nexedi/slapos!804