Create countdown to the date

[samit22]

Command

calendarN countdown 2022-11-28 10:00:00 --name=Name of the Countdown

The first argument should be `yyyy-mm-dd` format and the second is optional with hh:mm:ss time format in the local timezone 

If name is not given create name as countdown_to_2022_11_28_10_00_00 Should return:

 125 Days 12 Hours 57 Minutes 29 Seconds
``

Note: --cal=eng/nep needs to be done later.
--cal is English or Nepali calendar, accept `eng`, `nep` default is English

[samit22]

Closed from #14