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: Languages List

Abstacts the list of supported languages into
the LanguageModel class preventing use of
List. Also; fix a few cases where newer
logging techniques may have caused incorrect
logic flow.

Relates To #15534

Change-Id: I144fe4788abdaf0d93e53eeabc97b3f7aa2ec710
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3085
Reviewed-by: Adrien Destugues <pulkomandy@gmail.com>

HaikuDepot: Referencable Fixes

Some misuse of BReferencable / BReference are causing the
debugger to fire while debugging another issue. This
should fix some of it.

Change-Id: I895e209afe9e350e35b111739140c85133107227
Reviewed-on: https://review.haiku-os.org/c/haiku/+/2556
Reviewed-by: Adrien Destugues <pulkomandy@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>