feat(label): implement label color inheritance from dependent elements

[BQXBQX]

Implement the ability for labels to inherit colors from their associated graphical elements. This allows labels to automatically match the color of the elements they are describing.

• Add style inheritance in label creation
• Pass element style information to label callbacks
• Add test case to verify the implementation

Checklist

• npm test passes

• commit message follows commit guidelines

Description of change

This PR implements the ability for labels to automatically inherit colors from their associated graphical elements in G2 charts.

Labels can now access and inherit styles from their dependent elements through the label callback's fourth parameter. This enables seamless color matching between labels and their graphical elements.

chart
  .interval()
  .encode('x', 'genre')
  .encode('y', 'sold')
  .encode('color', 'genre')
  .label({
    text: 'genre',
    // Label color will automatically match its graphical element
    fill: (_, i, array, d) => d.elementStyle.fill
  });

[BQXBQX]

#5474

[coveralls]

Pull Request Test Coverage Report for Build 12177125260

Details

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 86.66%

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Totals
Change from base Build 12153668750:	0.0%
Covered Lines:	10611
Relevant Lines:	11866

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💛 - Coveralls

[hustcc]

另外，也帮忙改改文档中相关部分吧~ @BQXBQX

[hustcc]

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