PF4: React Virtualized table follow up issue

[priley86]

I would like to prerelease my changes in #2011 and begin testing downstream. There should be no breaking changes to @patternfly/react-table, however consumers should see the removal of Reactabular (reactabular-table) from their dependency tree.

Remaining things to circle back on later:

• tests
• convert flow js to typescript where necessary
• a11y implementation for virtualized (t.b.d.)
• fix Safari scrollbar in WindowScroller, this currently does not occur downstream (only in docs here) fixed in React-Virtualized PF4 tables #2011, padding should be applied for WindowScroller scrollbar

[rachael-phillips]

@priley86 can we create two new issues. 1 for tests and 1 for the a11y work? The reason being we're hoping to assign these out to team members.

[priley86]

done. Opened #2328 and #2329. Feel free to adjust accordingly @rachael-phillips :)