Bar chart bar value outline

[bivant]

Goals ⚽

BarChart - add ability to imitate bar shadows by outlines. An outline has a color and size (insets).
Example:

Implementation Details 🚧

IBarChartDataSet.swift - BarChartBarValueOutline

@objc open class BarChartBarValueOutline: NSObject
{
    @objc public var color: NSUIColor
    @objc public var insets: NSUIEdgeInsets
}

Do not draw the outlines if result bar width/height is less than 1. Stop drawing on the last outline that precedes that condition.
Value bar is a rect inside the outlines.
Border is drawn inside the outlines.

Testing Details 🔍

Tests for the narrow and wide bars are added. With and without the value labels.
Stacked bar test + same with value bar border.

[bivant]

CI failed - strange, xCode Version 11.6 (11E708) is able to compile the changes without any issues. Objc, Swift and Mac.

[bivant]

Hello.
CI is broken because of the tests. At the moment need to add "EXCLUDED_ARCHS[sdk=*]" = arm64; in the project settings to build tests locally. Additionally seems like reference screenshots are "broken", almost all tests fail even without my changes (master branch)

[4np]

This would be easy to accomplish by creating a custom renderer if #4297 was merged.