Charts Fixes for Swift 5.7 compiler

Issue Link :link:

I'm currently experimenting with the latest development Swift 5.7 toolchain and the Charts library was not compiling due to a bug in the implementation of RangeReplaceableCollection on ChartDataItem.

This PR fixes that by adding the missing protocol method and also fixes a couple of compiler warnings (which I think also exist on the latest stable toolchain).

More info on this here: https://github.com/apple/swift/issues/58737 - the reason this compiled pre-5.7 was due to a bug in Swift which was due to be fixed in 5.6, reverted and will ship in 5.7 by the looks of it.

Goals :soccer:

Library can now be compiled with Swift 5.7.

Testing Details :mag:

Library continues to compile under 5.6.

I wasn't able to get the snapshots to pass on my M1 Max laptop - maybe I'm using the wrong simulator. The failures were very subtle and I don't think are related to this change.

May 13 '22 23:05 lukeredpath

I also face other compiler errors:

EaseOutBack in ChartAnimationEasing.swift This fix worked for me https://github.com/danielgindi/Charts/pull/4836

    internal static let EaseOutBack = { (elapsed: TimeInterval, duration: TimeInterval) -> Double in
        let s: TimeInterval = 1.70158
        var position: TimeInterval = elapsed / duration
        position -= 1.0
        return Double( position * position * ((s + Double(1.0)) * position + s) + Double(1.0) )
    }

func drawDataSet in RadarChartRenderer.swift

        for case let set as RadarChartDataSetProtocol in (radarData as ChartData) where set.isVisible
        {
            drawDataSet(context: context, dataSet: set, mostEntries: mostEntries)
        }

CandleStickChartRenderer.swift

        for case let set as CandleChartDataSetProtocol in (candleData as ChartData) where set.isVisible
        {
              drawDataSet(context: context, dataSet: set)
        }

from: https://github.com/danielgindi/Charts/issues/4860#issuecomment-1178968435