Add Vietnamese dict

[folkevil]

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[CLAassistant]

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[thongvhoang]

Hi, thank you for the great work! I
I sent you a corpus for Vietnamese. The file was attached below.
vietnamese_dict.txt
vietnamese_dict.txt. This file gets from this research:
Download: https://github.com/VinAIResearch/dict-guided
You can evaluate on VinText dataset, text scene detection for Vietnamese, downloaded in Github.
Thank you.

[calibretaliation]

@thongvhoang are you still update the PR ? I can add another corpus and dict to process the vietnamese model faster..