pkgman: fix for syntax (help)

The tool "pkgman" was not showing it's help text
and this seems to be somehow related to the
initialization of constants such as
"kCommandCategoryPackages"; these values seems to
be coming through as empty-string for some reason.
I am changing those to be "#define" of regular
C-Strings and this seems to resolve the problem.
These values only seem to be used to group the
possible commands for production of the syntax or
help text - there do not seem to be any deeper
impacts beyond that functionality.

Change-Id: If9cd61462cd7f1f1b5ab2ece521bb3f00a1ba246
Reviewed-on: https://review.haiku-os.org/c/1139
Reviewed-by: waddlesplash <waddlesplash@gmail.com>
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

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 [un]install/update: Add non-interactive mode (-y)

Remove /boot/common for good

* Remove support for the "common" installation location from packagefs,
package kit, package daemon, package managers.
* Rename the B_COMMON_*_DIRECTORY constants referring to writable
directories to B_SYSTEM_*_DIRECTORY.
* Remove/adjust the use of various B_COMMON_*_DIRECTORY constants.
I'm sure some occurrence still remain. They can be adjusted when the
remaining B_COMMON_*_DIRECTORY constants are removed.

Refactor reusable pkgman code into libpackage

* Move RepositoryBuilder class to libpackage and add B* prefix to name.
* Pull BPackageManager class out of PackageManager and move to
libpackage. The base class is customizable via three handler objects
responsible for transaction handling, request execution, respectively
user interaction.
* Reorganize _ApplyPackageChanges(): Now we first prepare the
transactions for all affected installation locations (downloading
files etc.) and then commit them.

pkgman: add support for [un]installing/updating in system

pkgman uninstall: improve correctness

... with respect to inter-installation-location dependencies. E.g.
uninstalling a package from common should only uninstall packages
depending on it, when system doesn't still provide those dependencies.

We don't consider uninstalling packages from more specific installation
locations when dependencies are uninstalled from a more general one yet.

pkgman: PackageManager: Use flags instead of bools in ctor

pkgman [un]install: fix option '-H'

pkgman: Organize commands by category

pkgman: Add "uninstall" command

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 [un]install/update: Add non-interactive mode (-y)

Remove /boot/common for good

* Remove support for the "common" installation location from packagefs,
package kit, package daemon, package managers.
* Rename the B_COMMON_*_DIRECTORY constants referring to writable
directories to B_SYSTEM_*_DIRECTORY.
* Remove/adjust the use of various B_COMMON_*_DIRECTORY constants.
I'm sure some occurrence still remain. They can be adjusted when the
remaining B_COMMON_*_DIRECTORY constants are removed.

Refactor reusable pkgman code into libpackage

* Move RepositoryBuilder class to libpackage and add B* prefix to name.
* Pull BPackageManager class out of PackageManager and move to
libpackage. The base class is customizable via three handler objects
responsible for transaction handling, request execution, respectively
user interaction.
* Reorganize _ApplyPackageChanges(): Now we first prepare the
transactions for all affected installation locations (downloading
files etc.) and then commit them.

pkgman: add support for [un]installing/updating in system

pkgman uninstall: improve correctness

... with respect to inter-installation-location dependencies. E.g.
uninstalling a package from common should only uninstall packages
depending on it, when system doesn't still provide those dependencies.

We don't consider uninstalling packages from more specific installation
locations when dependencies are uninstalled from a more general one yet.

pkgman: PackageManager: Use flags instead of bools in ctor

pkgman [un]install: fix option '-H'

pkgman: Organize commands by category

pkgman: Add "uninstall" command