Adapt general logic to use underscores for JSON scope names

The inspector, renderer and system_description classes were adapted to
use underscores a separators for JSON scope names.
The usage of the the command line scope names wasn't changed though,
they still use dashes as separator.
Adapt unmanaged-files logic to use "_" for JSON

The unmanaged-files logic was adapted to use underscores as separators
for JSON scope names.
The usage of the the command line scope names wasn't changed though,
they still use dashes as separator.
Adapt config-files logic to use "_" for JSON

The config-files logic was adapted to use underscores as separators for
JSON scope names.
The usage of the the command line scope names wasn't changed though,
they still use dashes as separator.
Adapt changed-managed-files logic to use "_" for JSON

The changed-managed-files logic was adapted to use underscores as
separators for JSON scope names.
The usage of the the command line scope names wasn't changed though,
they still use dashes as separator.
Replace repeated Inspector.all_scopes call by attribute
Add CLI methods to convert scope names

Since scope names are now stored with an underscore internally we need
to convert them in both directions.
Both methods accept a string or an array and return an array because
the common use case is to have a list of scopes.