how can i set the legend text color when not selected in echarts 

### What problem does this feature solve?

if user want to see different / custom color on legend when its in disabled or in-active 

### What does the proposed API look like?

```
legend: {
    data: [
         {
          name: 'Email',
          textStyle: {
              color:['red', 'green']
             }
         }
      ]
}
```