Add info subgen to output lookup information

[sthzg]

yo subgenext:info lookup [--host=<hostname, ...>] [--subgen=<subgen1, ...>]
# Host     hostname    Found at /foo/bar/bam    Version 1.2.3
# Subgen   subgenname  Found at /foo/baz        Version 0.0.1
# ...

Both options are optional and allow for comma-separated enumeration of multiple names. The positional argument lookup is not really necessary atm, but allows for the info command to also solve different tasks in the future.