HaikuDepot: Change when featured packages are shown

 * Renamed the "Option" menu to "Show", removed the now redundant "Show" from
   the items in that menu.
 * Add an "Only featured packages" item in the Show menu. This item is disabled
   as soon as the user types something in the search terms field. Othetwise,
   this setting is respected, i.e. one can combine the featured setting with
   other settings, i.e. show all featured packages of a certain depot and in a
   certain category.
 * Added PackageInfo::IsProminent() and removed the respective method from
   the MainWindow (which only considered a package prominent if it was not
   yet installed).
 * "Show -> Installed packages" now defaults to on. There have been complaints
   on Trac and I guess rightfully so. The use-cases in which one starts
   HaikuDepot and wants to know about installed packages are just as likely
   as the use-case where one wants to install new software.
HaikuDepot: All "Show" settings are persistent now.
HaikuDepot: SharedBitmap: Enlarge maximum stream size

This is used for screenshots and some are larger than 128KiB.
HaikuDepot: Handle NULL PackageInfoRef in FeaturedPackagesView::Select()
HaikuDepot: Added PackagesListView::Select(PackageInfo)

which also scrolls the row into view (if it exists).
HaikuDepot: Sync the selection between normal and featured list