HaikuDepot : Improve Language Code Handling

HDS is soon going to be enhanced to deal with more than
just the two-character ISO language codes that it
currently supports. The logic in HD is currently expecting
that HDS will only supply these two character codes. This
change is about making adjustments to be able to cater to
any ICU language IDs from HDS.

The naming in HDS is still going to continue to use the
terminology that it currently does; it will call the
identifier for a language a "natural language code". The
HD source will instead reflect the nomenclature of ICU
and call the same thing a language ID.

Change-Id: Ib138c2e3b7b667edf15cd497c2f710f80b3c29f8
Reviewed-on: https://review.haiku-os.org/c/haiku/+/7424
Tested-by: Commit checker robot <no-reply+buildbot@haiku-os.org>
Reviewed-by: Niels Sascha Reedijk <niels.reedijk@gmail.com>

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: Drop Caches on Version Change

To avoid having to upgrade cache-data formats,
drop the caches when the application starts with
a different version from last time the
application launches.

Change-Id: I2f5b831b6a4fc570457bc633fd440a9021648b02
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3749
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

HaikuDepot: Lists; Categories + Stabilities

Remove use of custom list class where it is not
really required in the area of Categories. Also
introduces stabilities relayed over from the
Server and used in the HD user interface instead
of being hard-coded.

Relates To #15534

Change-Id: Ib71141e71cd4a0b4882827e2e59b62072de01b4b
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3331
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

HaikuDepot: Load Languages from HDS

The HaikuDepot application has, thus far had its
own hard-coded list of languages that the user is
able to choose when (a) creating a new account or
(b) creating a user-rating. This change will mean
that those languages are loaded from the HDS
server dynamically and in this way the user can
choose from the full list. There have also been
improvements to the way in which the languages are
displayed in the menu as well.

Change-Id: If7cb7b87f348ca59d503d276a22444e72d0e6168
Reviewed-on: https://review.haiku-os.org/c/1425
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

HaikuDepot: Process and Data-loading Improvements

This change is a reshuffle of the backend processing involved in the
aquisition of data from servers including the pull-down and load of
HPKR data as well as the pull-down and load of data from the
HaikuDepotServer (HDS) system. The driver for this change is to
implement an initial implementation of a progress bar for the
loading of data as the application starts.

The following are notable changes;

* Removed some previously attempted 'functional style' logic in the
model which didn't fit well with C++
* Use of the base-url in the logical mapping from HDS and HD data is no
longer required and has been removed
* Some logging has been improved making it clearer which part of HD
is producing the logging which in turn helps with debugging issues
* List class has been modified to more cleanly support sorted lists
and binary searches; tests have also be updated accordingly
* Reorganise and tidy-up of the data-loading processes' structures
* The local repository update (HPKR) and data-load occur in background
processes now in the same system as the HDS data-load - this has been
crudely shifted from the MainWindow to new Processes and incorporated
into the background processing system
* The 'state-machine' background process runner is now replaced with a
'coordinator' style approach that can more easily handle the new
processes related to HPKR loading.
* Progress for loading processes is shown in the main window in the
WorkStatusView - this is flickering a bit, but basically works
* Added some documentation regarding how Processes work in the system
* The "Refresh Repositories" menu item now also updates data from HDS
* The "Refresh Repositories" menu item is disabled when the background
processes are running that update the repository data

Some further refinement would be good, but this change is large enough
for one round of improvements. There is an issue that the status bar
is used for screenshot display as well as this data-loading, but that
was the case before so it is something that can be dealt with later if
it is a problem.

Change-Id: I7668307645e3aabaf7e4a6e37e2cca80cc0f489e
Reviewed-on: https://review.haiku-os.org/770
Reviewed-by: waddlesplash <waddlesplash@gmail.com>