feat(polar): Intent to ship polar type

[netil]

Issue

#2462

Details

Implementation of polar type

// Polar options
polar: {
    level: {
        depth: 5,
        max: 150,	
        text: {
            show: true,
            backgroundColor: "yellow",
            format: function(level) {
                return `Level: ${level} `;
            }
        },
        show: false
    },
    label: {
        show: true,
        format: function(value, ratio, id) {
            return `${value}\n(${(ratio * 100).toFixed(0)}%)`;
        },
        ratio: 1,
        threshold: 0.25
    },
    padAngle: 0,
    padding: 0,
    startingAngle: 1.5
},

[coveralls]

Coverage increased (+0.01%) to 90.315% when pulling a26a540 on netil:polar#2462 into 948edd2 on naver:master.