API for increasing and decreasing for CandleStick Chart

In the CandleStickRenderer.
The colors of candle are determined by `open` and `close` values. But in my case (maybe a lot others are same as mine), the colors are determined by the last candleEntry too.

If the the increasing and decreasing had an API the default imp are `open > close` as currently doing. But users also can override, it would be perfect
Please see below, It's very easy to draw colors or hollow candles when drawDataSet.

```
enum Trend {
increasing,
decreasing,
neutral
}

Trend trendOfEntry(entry) {
if open > close {
return .decreasing
} else if open < close {
return .increasing
} else {
return . neutral
}
}
```

Old code
```
if dataSet.shadowColorSameAsCandle
{
if open > close
{
shadowColor = dataSet.decreasingColor ?? dataSet.color(atIndex: j)
}
else if open < close
{
shadowColor = dataSet.increasingColor ?? dataSet.color(atIndex: j)
}
else
{
shadowColor = dataSet.neutralColor ?? dataSet.color(atIndex: j)
}
}
```

Start in CandleStickRenderer and follow the drawDataSet path where increasing, decreasing, and neutral colors are selected from open and close values. Define the requested override behavior while preserving the current open/close defaults, then verify candle and shadow colors for increasing, decreasing, and neutral entries.

Written by the indexing model from the issue text.