Add support for json output

[samit22]

Add a flag at the root level to support JSON output as well

eg:

calendarN today -j

Should return JSON output

{
    "english": {
        "year": 2022,
        "month": 8,
        "day": 18,
        "week_day": 0,
        "full_date": "Sunday, 24 July, 2022",
        "year_days": 130,
        "week": 20,
        "progress": 56.3
    },
    "nepali": {
        "year_english": 2079,
        "month_english": 1,
        "day_english": 8,
        "week_day_english": 0,
        "year_days": 101,
        "week": 20,
        "progress": 35.3,
        "year": "२०७९",
        "month": "बैशाख",
        "day": "०८",
        "week_day": "आइतवार",
        "full_date": "आइतवार, ०८ श्रावण, २०७९"
    }
}