Export the vertical text languages outside of imagetranslation file

[maeriil]

Currently we have a variable called vertical_langauge that contains the following contents

vertical_langauges = [
    "japanese",
    "mandarin",
]

This is used so that when the source language is one of these languages, we will need to rotate the image to better detect the texts.

def is_lang_vertical_lang(lang: str) -> bool:
    return lang in vertical_langauges

However, we shouldn't be setting this in our current file, imagetranslation.py. We need to create a seperate file and add these logics into it. The location of this file is open for discussion.