Feat heikin ashi bars

[Basttyy]

(Feat) Implement heikin ashi bars

Summary

This PR implements Heikin Ashi candle type.

Changes Made

1. getDataList now supports a boolean flag to determine if the data returned should be mutated to fit the selected candle type

2. Candle type style option now supports type 'heikin_ashi' which will make the chart display Heikin Ashi candles

Usage Example

const chart = init('container-div', {
  styles: {
    candle: {
      // 'candle_solid' | 'candle_stroke' | 'candle_up_stroke' | 'candle_down_stroke' | 'ohlc' | 'area'
      type: 'candle_solid',
    }
  }
})

Benefits

Users will now be able to use Heikin Ashi Candle type on their charts

Testing

✅ TypeScript compilation successful
✅ Build passes (ES and UMD modules)
✅ Type definitions generated correctly
✅ Manual testing carried out on sample project
✅ No breaking changes to existing API

Breaking Changes

None. This is a non-breaking additive change.

Sample Screenshot

Notes: There are merge conflict because my fork has merged some PR's which are still unmerged on this Repo. Hence those PR's have to be merged first