Add VietNam lunar calendar

[culy247]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (973d8b6) 100.00% compared to head (4372f35) 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##            master      #214    +/-   ##
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  Coverage   100.00%   100.00%            
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  Files           22        23     +1     
  Lines         2965      3502   +537     
==========================================
+ Hits          2965      3502   +537     

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[culy247]

@gouguoyin Review pr for me

[gouguoyin]

I am planning to reconstruct the calendar. Each calendar is an independent package.so not accept PR until the specific plan is finalized.

[culy247]

I am planning to reconstruct the calendar. Each calendar is an independent package.so not accept PR until the specific plan is finalized.

@gouguoyin Thank you, you can shame me your plan?

[gouguoyin]

It's not finalized yet, do you have any good ideas?

carbon.CreateFromCalendar(c Calendar)
carbon.ToCalendar(c Calendar)

[gouguoyin]

You can refer to the latest Chinese Lunar to contribute VietNam lunar calendar，must include CreateFromSolar and CreateFromVLunar methods

[culy247]

You can refer to the latest Chinese Lunar to contribute VietNam lunar calendar，must include ToGregorian and ToVLunar methods

thank you.