pkgman: Add --debug option for most commands

* Add CommonOptions class and add an instance to Command. It supports a
debug level.
* full-sync, install, search, uninstall, update: Add option --debug.
This allows getting some debug output from the solver in cases where
the result seems weird.

pkgman: Add --debug option for most commands

* Add CommonOptions class and add an instance to Command. It supports a
debug level.
* full-sync, install, search, uninstall, update: Add option --debug.
This allows getting some debug output from the solver in cases where
the result seems weird.