Implement `enum class TranslationFile`

[kphoenix137]

Creates function GetTrn() along with an enum class. All trn files will be represented in the enum class and TrnFileLoc table rather than only the trn files that get used in game, allowing more accessible usage to trn files without having to look up the file names in the game assets mpq.

Note: Every monster classification contains an enum for the default colors they use, even though that enum is always nullptr since there is no associated trn file. This is just for ease of use when selecting translation files to use, since there is no way to know the colors that the monster will use by default unless you view them in game without a translation file, or open them up in a graphics tool.