Feature/accessibility group component

[ljones87]

• Adds an AccessibilityGroupComponent to victory-core.
• This component can be provided to the groupComponent prop to add aria-labels and desc tags with aria-describedby.
• Also adds aria-label to groupComponent option VictoryClipContainer
• tests

[boygirl]

I think aria-describedby belongs on the g tag. When there is a desc, aria-describedby should use the id of the desc tag. When there isn't a desc, it should use whatever user provided id string.

[ljones87]

ok cool, yeah I didn't get a lot out of looking up aria-describedby best practice, but in looking up reading on the <desc> tag i see its placement on <desc> is redundant. Will fix

[boygirl]

Also, when there is a desc, there needs to be a back up for if the user doesn't provide a descId

[ljones87]

OK found a better resource to understand the described by attribute, https://developer.paciellogroup.com/blog/2018/09/describing-aria-describedby/

as you had said, aria-describedby and descId should be identical, with aria-describedby using the descId
I am wondering if aria-describedby should even be a prop the user controls:

if(descId) => descId is required, aria-describedby will use the same input
else arial-label should suffice

[boygirl]

Hmm... I think aria-describedby should still be a prop in the case where a user wants to describe the group with some other, non-victory element. If they provide both a desc prop and a aria-describedby prop, though, the user's aria-describedby should be used to set the descId so that they definitely match. If they provide only a desc and no aria-describedby we will need to generate an id to use for both aria-describedby and descId. So, I think descId probably shouldn't be a prop.

[boygirl]

@ljones87 This looks great! Good to merge, I think.