feat(CEECORE-2818): upgrade to React 18 RC, document issues

[coston]

Description

The React 18 Release Candidate is available, and React 18 will enable several enhancements when it comes to module federation. This branch is a proving ground of what is required to upgrade what React is released and surface any issues with breaking changes.

• [x] Upgrade dependencies to React 18
• [x] Upgrade packages to use React 18 conventions, to the point of issues or excessive refactor
• [x] Upgrade subapp 1 samples to React 18
• [x] Upgrade subapp 2 samples to react 18

Known issues from the upgrade

• ⛔️ Critical: renderToStaticNodeStream adds trailing comment nodes to any text node, breaking render, tests fail
• ⛔️ CSR innerHtml is broken when using createRoot, tests fail
• Updates/Deprecations to React 18 Server Rendering APIs call for thoughtful refactor of subapp-react's framework-lib
• renderToNodeStream will work in 18, including the new Suspense features described below, but it will buffer the entire content until the end of the stream. In other words, it will no longer do streaming.

Screenshot

[CLAassistant]

All committers have signed the CLA.