Overhauled (and moved) libsite

Now that there is a libsh, it makes sense to move libsite there.

Took this opportunity to clean up the long list of messy global
environment variables therein, and thus did the same for each use-case
of these variables.
module/util util:secret() WIP
... lib/libsh/libsite/unit/dynamic.csv
... lib/libsh/libsite/unit/static-util.sh
... module/mongo