[Feature] Have the ability to have the same Y-axis on both sides of chart

### What problem does this feature solve?

This feature would provide the ability to have the exact same Y-axis on both sides of the chart. This issue has been raised before but apparently has never been implemented. For example, https://github.com/apache/echarts/issues/11589

This would be a very useful feature.

### What does the proposed API look like?

API already has the "position" property ("left" or "right") for the yAxis. Add a "both" option. The right y-axis would be a mirror image of the left y-axis.