Support projects with prefixed translation file names

[WULCAN]

I don't think the assumption that translation files are always named ^[language-code].[ext]$ is a good one. I have a project of my own where some of my translation files have names like devise.en.yml. It's a framework-level naming convention that's outside of my control and which makes Lyra unviable for those strings even despite the two letter language codes.

Originally posted by @henrycatalinismith in #106 (comment)