Feat/reworked language codes (#865)

* Reworked language codes to use Steam localization standards

* Reworked language codes tweaks (#864)

* Language code rework tweaks

* Update bg.lua

* Reevaluate whether a language is WIP

* Update bg.lua

* Even better mark for languages as WIP (> 80% translated)

* Update zh_cn.lua

* Update cs.lua

* Fix for game language codes

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Co-authored-by: kittenchilly <mario.pikmin.zelda@gmail.com>

descriptions/ab+/vi.lua

@@ -10,10 +10,11 @@
 
 local languageCode = "vi"
 
--- init en_us table
+-- init Vietnamese table
 EID.descriptions[languageCode] = {}
 EID.descriptions[languageCode].custom = {} -- table for custom entity descriptions
 EID.descriptions[languageCode].languageName = "Vietnamese"
+EID.descriptions[languageCode].alternativeLanguageCodes = {"vietnamese"}
 
 -- Fonts to be used with this language pack
 EID.descriptions[languageCode].fonts = {{name="vi_vn"}, {name="vi_vnborderless"}}