add support for Hakka (pha̍k-fa-sṳ romanization)

[kalvinchang]

Sources:

• https://en.wiktionary.org/wiki/Wiktionary:About_Chinese/Hakka
• https://en.wikipedia.org/wiki/Sixian_dialect to fill in certain diphthongs / triphthongs that the above link missed
• https://en.wiktionary.org/wiki/Module:hak-pron (Wiktionary's PFS to HRS to Sinological IPA conversion module)

I chose PFS (pha̍k-fa-sṳ) over Taiwan Ministry of Education's 客家語拼音方案 (HRS on Wiktionary) because Wiktionary lists entries for Northern Sixian in PFS. I chose Northern Sixian because it is one of the dialects that consistently appears in Wiktionary Hakka entries.

While moedict.tw lists data for 6 dialects in HRS (Sixian, Hailu, Dapu, Raoping, Zhaoan, Nansixian), Wiktionary may potentially have more entries than moedict.tw. Furthermore, conversion between PFS and HRS can be and has been done automatically (see links below)

Another note is that we do not mark extra short vowels, unlike https://en.wikipedia.org/wiki/Sixian_dialect

Further notes that may helpful for posterity:

• moedict.tw's API endpoint for Hakka data across 6 dialects (HRS) https://github.com/g0v/moedict-webkit/tree/master/h
• https://ws.moe.edu.tw/001/Upload/6/relfile/7803/38403/67447334-bef4-4c69-bc24-32090b745031.pdf Ministry of Education's grapheme to phoneme charts for 客家語拼音方案 and each of the 6 main dialects in Taiwan (Sixian, Hailu, Dapu, Raoping, Zhaoan, Southern Sixian/Nansixian)
• https://github.com/g0v/moedict-webkit/blob/35af25fe8f086eec666a4c1057ae4af739447b4c/view.ls - Ministry of Education's moedict.tw conversion tool between HFS and PFS that is applied on the front end
• Wiktionary uses Guangdong Romanization for entries in the Meixian dialect
• Wiktionary's dump only stores the PFS (Northern Sixian) and Guangdong Romanization (Meixian) versions, so the HRS / Sinological IPA conversion is done on the front end

[kalvinchang]

In addition, we do not have separate entries for <kh(i)>, <h(i)>, and <k(i)> because Northern Sixian does not distinguish between those and kh, h, and k respectively, although Meixian dialect does