Added functionality to be able to pass user props to components. Safe…

[dlcartright]

Description:

Passed missing 'title' and 'desc' props to VictoryContainer component from VictoryChart component. Added functionality for users to pass other attributes to the container SVG that pass the whitelist test (defined in victory/packages/victory-core/src/victory-util/user-props.js). Safe-list currently allows props starting with 'aria-' and 'data-'. VictoryChart, VictoryGroup, VictoryStack, and VictoryContainer have all been wired up to allow these user props. More components to follow.

Currently the whitelist contains 2 arrays called "startsWith" and "exactMatch". Any props will be run against these two to see if they start with any of the items in the startsWith array or they match exactly with items from the exactMatch array.

Testing:

Start this branch with yarn start and navigate to the Chart example.

Test 1

1. Inspect the first chart in DevTools, you will see an attribute added to the SVG called "data-some-user-prop" as well as an "aria-label".
2. Any of other attributes passed into VictoryChart (that are allowed in the whitelist) will be added here as well. So, if you wish, add additional attributes to the example and inspect to see that they carried over.
   

Test 2

1. Using the browser extension called Accessibility Insights for Web run a Fast Pass on the chart example page.
2. The first 4 charts will be accessible (because they have a title attribute added to them). The others will be outlined in red and show the error below. It is up to the user to add the title to their charts.

[dlcartright]

Will be making additional PRs into this branch for the remaining components to break up the work and keep the PRs manageable.

[becca-bailey]

I'm not sure whether this useMemo is doing any good here. Since initialProps isn't stored in a state or ref value, I believe useProps will be re-calculated on every render. There is a fairly good explanation here on how to compare objects in hooks. https://stackoverflow.com/questions/54095994/react-useeffect-comparing-objects

For now, I wouldn't stress too much about memoizing this value since it isn't a very expensive function call. Unless you can see a performance difference, let's just remove the useMemo for now.

[becca-bailey]

Where is parentProps.userProps coming from? Is this outdated, or are we still setting this somewhere in a getComponentProps function?

[becca-bailey]

I have a couple questions and comments here, but let's merge this work into feature/user-props, and you (or anyone else who picks up the work) can address these comments in a follow-up PR to the same feature branch. I will also change your other PRs to merge into the feature branch, rather than into this one.