feat: implement localization system (#716)

* lib/localization: implement localization system

Locale files are placed in lib/localization/locales/. If you add a
locale, update manifest.json with available locales.

* Exclude locales from check spelling

* tests(lib/localization): add comprehensive translations test

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix(challenge/metarefresh): enable localization

Signed-off-by: Xe Iaso <me@xeiaso.net>

* fix: use simple syntax for localization in templ

Also localize CELPHASE into French according to the wishes of the
artist.

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: spelling

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore:(js): fix forbidden patterns

Signed-off-by: Xe Iaso <me@xeiaso.net>

* chore: add goi18n to tools

Signed-off-by: Xe Iaso <me@xeiaso.net>

* test(lib/localization): dynamically determine the list of supported languages

Signed-off-by: Xe Iaso <me@xeiaso.net>

---------

Signed-off-by: Xe Iaso <me@xeiaso.net>
Co-authored-by: Xe Iaso <me@xeiaso.net>

docs/docs/CHANGELOG.md

@@ -11,6 +11,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+- Implement localization system. Find locale files in lib/localization/locales/.
+
 ## v1.20.0: Thancred Waters
 
 The big ticket items are as follows: