feat(type): provide ability to extend series option

[pissang]

Brief Information

This pull request is in the type of:

• bug fixing
• new feature
• others

What does this PR do?

Previously we can't use TypeScript declaration merging feature to extend our SeriesOption in the extensions like echarts-wordcloud because it's a union type.

This PR adds an interface RegisteredSeriesOption. It can be extended with new types of series. SeriesOption will pick all its values and get a union type.

import echarts from 'echarts';
declare module 'echarts/types/dist/echarts' {
   interface RegisteredSeriesOption {
      wordCloud: WordCloudSeriesOption
   }
 }

[echarts-bot]

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[echarts-bot]

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