Add Vietnamese braille translation table to NVDA

[tmthywynn8]

According to vi-g1.ctb's history page, the Vietnamese Grade 1 table has been available since February 13, 2015. It is, according to the headers, based on fr-fr-g1.utb, and supports Unicode-encoded Vietnamese text, as opposed to TCVN3 or VNI. From a brief look at the code table, it does match with the Vietnamese Braille code found on Sao Mai Education Fund's site. Unlike vi.ctb, this table was actually created by Harri Pasanen, rather than automatically generated by ttbtest.

For the reasons above, I believe that vi-g1.ctb's should be added to NVDA in order to support Vietnamese Grade 1. vi.ctb appears to be a Vietnamese 8-dot computer braille table, but I am unsure of its viability, not having an actual reference page for it.