Update to React 17

[scurker]

Once #1159 is complete, we should upgrade as a half-step to React 17. This should include both react and react-dom for development dependencies in the following packages:

• ./ (root)
• packages/react

No changes needed for peerDependencies until React 18 (see #631)

Also see https://legacy.reactjs.org/blog/2020/08/10/react-v17-rc.html for a reference of changes that may be needed. Running the newly updated tests should be sufficient to see if any specific issues are caught as the result of the upgrade.

[scurker]

I've performed a functional assessment of each component to determine their compatibility with React 17. This is by no means comprehensive, but is testing the expected behavior of each component and if there are any regressive behaviors with React 17:

• ✅ Accordion
• ✅ Address
• ✅ Alert
• ✅ Breadcrumb
• ✅ Button
• ✅ Checkbox
• ✅ ClickOutsideListener
• ✅ Code
• ✅ Combobox
• ✅ DescriptionList
• ✅ ExpandCollapsePanel
• ✅ FieldWrap
• ✅ Icon
• ✅ IconButton
• ✅ Layout
• ✅ Line
• ✅ Link
• ✅ Listbox
• ✅ Loader
• ✅ LoaderOverlay
• ❌ Modal (confirmed issue, see Bug: Modal broken in React 17+ #1087)
• ✅ NavBar
• ✅ Notice
• ✅ Offscreen
• ❌ OptionsMenu (confirmed issue, see Bug: OptionsMenu broken in React 17+ #830)
• ✅ Pagination
• ✅ Panel
• ❌ Popover (confirmed issue, likely related to either Bug: Modal broken in React 17+ #1087 and Bug: OptionsMenu broken in React 17+ #830)
• ✅ ProgressBar
• ✅ RadioCardGroup
• ✅ Scrim
• ✅ SearchField
• ✅ Select
• ✅ SkipLink
• ✅ Stepper
• ✅ Table
• ✅ Tabs
• ✅ Tag
• ✅ TagButton
• ✅ TextEllipsis
• ✅ TextField
• ✅ Timeline
• ✅ Toast
• ✅ Tooltip
• ✅ TooltipTabstop
• ✅ TopBar
• ✅ TwoColumnPanel