feat: candlestick chart support CandleMarkerPainter

[artshooter]

Hi, I've made improvements and refinements based on the feedback from the previous PR.

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Feature Summary

This PR adds a candle marker system to CandlestickChart for marking trading signals on candlestick charts.

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Key Features:

• CandleMarkerPainter - Abstract base class for custom candle marker implementations
• BuyAndSellSignalPainter - Built-in implementation with flexible condition-based signal detection,
  customizable bubble styles and labels to easily extend various trading signal scenarios

[SAGARSURI]

Can I draw a line to show trade indicators? Something like this:

[artshooter]

@SAGARSURI
Unfortunately, this PR implements buy/sell signal markers on individual candles, not horizontal lines across the chart. The screenshot shows an order line feature that displays price lines, position size, and P&L information. These are fundamentally different features, which are not currently supported.