HaikuDepot : Refactor Screenshots

Rework the way in which the application deals
with screenshots so that there is a repository
of screenshots that is referenced from
identifiers on the package model and not that
the screenshot bitmaps are stored with the
model and not cleaned up.

Change-Id: I632def96852a518b3f6b1c8b81909de117bbbc54
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7296
Reviewed-by: Andrew Lindesay <apl@lindesay.co.nz>

HaikuDepot: Background Processing

Unify the background processing in the
application to one system and refactor
the package actions. This won't fix
any specific current issues with this
area, but lays the ground for later
fixes.

Change-Id: I098b81e7afc4aeb883bddf1acfc01f7888134257
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3997
Reviewed-by: Andrew Lindesay <apl@lindesay.co.nz>

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: UI Colouring Fix

Some text displayed was not using the system
standard colors.

Resolves #11689

Change-Id: Ia415a32f47dff6aa86d343d1acc154527300e924
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2493
Reviewed-by: waddlesplash <waddlesplash@gmail.com>

HaikuDepot: Added rudimentary screenshot window.

Clicking the thumbnail in the package info area will now open a
window where the full-size screenshot is downloaded and shown. There can
only be one such screenshot window open. Navigating between multiple
screenshots of a package is not yet implemented. Also, no caching, but
this may be OK as it is, since one usually looks at these only once and
doesn't want the harddrive filling up with screenshots.

HaikuDepot: Separate MessagePackageListener...

...into MessagePackageListener and OnePackageMessagePackageListener.
The first one doesn't know which package(s) it's listening to. But it
can filter the change notifications now and only react to certain changes.
The second one knows which package it's listening to.

HaikuDepot: Extracted MessagePackageListener...

... from PackageInfoView into its own files.

HaikuDepot: Remember PackageInfoRef in PackageInfoView

* Added getter

HaikuDepot: Organized source into sub-folders

HaikuDepot: Added rudimentary screenshot window.

Clicking the thumbnail in the package info area will now open a
window where the full-size screenshot is downloaded and shown. There can
only be one such screenshot window open. Navigating between multiple
screenshots of a package is not yet implemented. Also, no caching, but
this may be OK as it is, since one usually looks at these only once and
doesn't want the harddrive filling up with screenshots.

HaikuDepot: Separate MessagePackageListener...

...into MessagePackageListener and OnePackageMessagePackageListener.
The first one doesn't know which package(s) it's listening to. But it
can filter the change notifications now and only react to certain changes.
The second one knows which package it's listening to.

HaikuDepot: Extracted MessagePackageListener...

... from PackageInfoView into its own files.

HaikuDepot: Remember PackageInfoRef in PackageInfoView

* Added getter

HaikuDepot: Organized source into sub-folders