[Feature] Y -axis left value style custom -position support `margin`

[cbbfcd]

What problem does this feature solve?

Just like the scene in the picture, I need to make the gradient background longer, but it is always the center. It cannot be set up at the top of the top through Margintop.

What does the proposed API look like?

margin: [40]

[github-actions]

This issue has been automatically marked as stale because it did not have recent activity. It will be closed in 7 days if no further activity occurs. If you wish not to mark it as stale, please leave a comment in this issue.

[github-actions]

This issue has been automatically closed because it did not have recent activity. If this remains to be a problem with the latest version of Apache ECharts, please open a new issue and link this to it. Thanks!