feat(event): provide label index in axis events

[Ovilia]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Provides label index and formatted label in axis label events.

Fixed issues

#15798

Details

Before: What was the problem?

No index info, so the user cannot be sure about which label of the axis is clicked.

After: How is it fixed in this PR?

Two params are provided: index for label index and formattedLabel for formatted label.

Misc

• The API has been changed (apache/echarts-doc#xxx).
• This PR depends on ZRender changes (ecomfe/zrender#xxx).

Related test cases or examples to use the new APIs

N.A.

Others

Merging options

• Please squash the commits into a single one when merging.

Other information

[echarts-bot]

Thanks for your contribution!
The community will review it ASAP. In the meanwhile, please checkout the coding standard and Wiki about How to make a pull request.

The pull request is marked to be PR: author is committer because you are a committer of this project.

Document changes are required in this PR. Please also make a PR to apache/echarts-doc for document changes and update the issue id in the PR description. When the doc PR is merged, the maintainers will remove the PR: awaiting doc label.

[echarts-bot]

Congratulations! Your PR has been merged. Thanks for your contribution! 👍