[Issue 4782] Add AudioGraphSupportChart

[e-sung]

Issue Link :link:

https://github.com/danielgindi/Charts/issues/4782

Goals :soccer:

• For visually impaired end users, they should be able to get quick grasp of the chart by using AuidoGraph feature.
• For developers who use this library, I want them to be able to get benefits of AudioGraph out of the box. That is, I want to offer them default implementation for AudioGraph support.
• But if developers want to use their own implementation for AudioGraph support, they should be able to do that.

Implementation Details :construction:

Most of the logics are held within new AudioGraphSupportChart protocol, so that it can be read and understood in seperate context.

BarLineChartViewBase conforms to AudioGraphSupportChart, because it is the most basic chart class that has X and Y axis, which is required for chart to be represented as AudioGraph.

There are few following changes in BarLineChartViewBase

1. Add necessary stored properties for AudioGraphSupportChart conformation
2. Call automaticallyUpdateYAxisForSelectedEntry in initialization so that yAxis that AudioGraph depend on can be updated everytime VoiceOver focus has changed.
3. In notifyDataSetChanged, call updateAccessibilityChartDesciptor so that AudioGraph can be updated to the latest data.

Most of added code will be executed only when VoiceOver is running.

Testing Details :mag:

https://user-images.githubusercontent.com/4796743/156188863-dee5a476-719c-4b15-8c7d-70822b1226e8.mp4

https://user-images.githubusercontent.com/4796743/156189678-a29e1ad3-b9e1-4338-8f27-7ae31b5851d3.mp4

https://user-images.githubusercontent.com/4796743/156189972-3d105be4-d6a2-4ef7-8e32-8e3594d72dd6.mp4

https://user-images.githubusercontent.com/4796743/156190307-55c9914a-e71f-4443-8c42-92faa8dd6032.mp4

https://user-images.githubusercontent.com/4796743/156190562-745d4534-805d-4cee-ae5a-6918fbafb47e.mp4

https://user-images.githubusercontent.com/4796743/156190779-17c519cd-3873-4ee2-8c16-d3b981e3e4e3.mp4