Crash at BarChartRenderer when render bat with multiple data sets

[truongtho1603]

• I've read, understood, and done my best to follow the *CONTRIBUTING guidelines.

What did you do?

Given that I have an array of BarChartDataSet which is let dataSets [4 entries, 3 entries, 1 entry].
Then I make a BarChartData(dataSets: dataSets) with that set.
When I render the bar chart with that data set it will crash at BarChartRenderer.

accessibilityOrderedElements[j/stackSize].append(element)

with an out of exception of index out of range.

What did you expect to happen?

It should not crash.

What happened instead?

I found out that the ChartData > maxEntryCountSet implementation is wrong.
It returns 1 in my example in stead of 4.
I think the fixing should be

/// The DataSet object with the maximum number of entries or null if there are no DataSets.
    @objc open var maxEntryCountSet: Element?
    {
        return self.max { $0.entryCount < $1.entryCount }
    }

Charts Environment

Charts version/Branch/Commit Number: 4.0.2
Xcode version: 13.2.1
Swift version: 5.2.4
Platform(s) running Charts: iOS
macOS version running Xcode: 12.3

[truongtho1603]

PR https://github.com/danielgindi/Charts/pull/4822/files