[Feature] Add new positions to series-bar.markLine.data.0.label. position

[isabellachen]

What problem does this feature solve?

When markLines exist very close together on yAxis, it is hard to read.

I have tried offsetting vertically with distance and padding but both don't seem to move the label in the vertical axis.

What does the proposed API look like?

Along with label positions: 'start', 'middle', 'end', 'insideStartTop', 'insideStartBottom', 'insideMiddleTop', 'insideMiddleBottom', 'insideEndTop', 'insideEndBottom', to add 'endTop' and 'endBottom'.

option = {
  xAxis: {
    type: 'category',
    data: ['Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun']
  },
  yAxis: {
    type: 'value'
  },
  series: [
    {
      data: [150, 230, 224, 218, 135, 147, 260],
      type: 'line',
            markLine: {
        data: [
             {
            type: 'test',
            name: 'test',
            yAxis: 197,
            label: {
              backgroundColor: 'pink',
              distance: [20, 300],
              padding: [50,0,0,0]
            }
          },
          {
            type: 'average',
            name: 'Avg',
          }
        ]
      }
    }
  ]
};

[isabellachen]

Use offset instead of distance to manually position the label.