HaikuDepot: Screenshot List

Remove the use of custom list class related to
screenshots on a package.

Relates To #15534

Change-Id: I8289c25ef0ab5a6715dd9c6c83b6602a25d2f544
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3549
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

HaikuDepot: Icon / Tarball Handling

Instead of exploding the tar-ball of icons from
HDS, keep it as a tar-ball, index it and read
data directly out from specific indicies on demand.

This will speed up the process of downloading
the icons by removing the unpack. Also updates
will be faster by avoiding the need to delete the
old icon files.

Because icons are loaded on-demand, the start
time is faster by avoiding all the icon loads.
There are also savings on memory consumption.

Indexing on each load is surprisingly fast so
no external index is maintained. Likewise for
the tar-balls's meta-data.

This commit does not cover the implementation
of an LRU cache of the icons in memory.

Relates to #15370

Change-Id: Ia1647d8c805be89618f493d2592bf7877fca3f14
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3205
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

HaikuDepot: add icons to screenshot window tool bar

* Arrow icons instead of text for previous/next buttons

HaikuDepot: Split generic and specific UI classes

* Also fixed placement of PackageManager which I must have
dropped into the wrong folder by accident.

HaikuDepot: Split generic and specific UI classes

* Also fixed placement of PackageManager which I must have
dropped into the wrong folder by accident.