Add support for authentication when retrieving remote data

New --user and --password options for latest, download, install
and update subcommands.

Signed-off-by: Louis-Francis Ratté-Boulianne <lfrb@collabora.com>
Reviewed-by: Justin Kim <justin.kim@collabora.com>
Differential Revision: https://phabricator.apertis.org/D4920