We originally used `pt_PT` (i.e. Portuguese (Portugal)) to distinguish with
the Brazilian Portuguese variant `pt_BR`, as both are significantly different
and need separate translation files.
But Portugal's Portuguese (or "European Portuguese") is close to the variant
spoken and written in other Portuguese-speaking countries such as Angola and
Mozambique, so it makes sense for users of these countries to also have access
to the European Portuguese translation (at least until translators decide that
adding e.g. `pt_AO` and `pt_MZ` variants would make sense, taking into account
the translation effort that this duplication implies).
Godot's locale matching checks first for the full locale (e.g. `pt_AO`), and
if no translation is found, it checks for the non-regional language code
(`pt`), so this change enables translations for Portuguese speakers outside
Portugal and Brazil.
(cherry picked from commit 1e2f55e273)
