Enable support for React 18

[adamstankiewicz]

Related PRs:

• Enable support for React 18 frontend-build#625
• Enable support for React 18 frontend-platform#763

The Open edX MFEs are overdue to support React 18 (especially as React 19 is already out now, too). Some efforts have been started to support React 18 in the shared JavaScript libraries, such as Paragon (openedx/paragon#3367, v22 and v23).

By enabling support for React 18 (should be additive-only), we can further enable incremental migration to React 18 within MFEs. Most of the changes are within the example MFE included in this repository for testing.

The React 18 Upgrade Guide was followed.

Merge checklist:

• Evaluate how your changes will impact existing consumers (e.g., frontend-app-learner-portal-enterprise, frontend-app-admin-portal, and frontend-app-enterprise-public-catalog). Will consumers safely be able to upgrade to this change without any breaking changes?
• Ensure your commit message follows the semantic-release conventional commit message format. If your changes include a breaking change, ensure your commit message is explicitly marked as a BREAKING CHANGE so the NPM package is released as such.
• Once CI is passing, verify the package versions that Lerna will increment to in the Github Action CI workflow logs.
  • Note: This may be found in the "Preview Updated Versions (dry run)" step in the Github Action CI workflow logs.

Post merge:

• Follow the release steps in the README documentation. Verify Lerna's release commit (e.g., chore(release): publish new versions) that incremented versions in relevant package.json and CHANGELOG files, and created Git tags for those versions is on master (Important: ensure the Git tags are for the correct commit SHA).
• Run the Publish from package.json Github Action workflow to publish these new package versions to NPM.
  • This may be triggered by clicking the "Run workflow" option for the master branch.
• Verify the new package versions were published to NPM (i.e., npm view <package_name> versions --json).
  • Note: There may be a slight delay between when the workflow finished and when NPM reports the package version as being published. If it doesn't appear right away in the above command, try again in a few minutes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 79.01%. Comparing base (c317ac0) to head (1c649e1).
Report is 33 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #432      +/-   ##
==========================================
- Coverage   79.08%   79.01%   -0.07%     
==========================================
  Files          35       37       +2     
  Lines         698      753      +55     
  Branches      179      191      +12     
==========================================
+ Hits          552      595      +43     
- Misses        133      145      +12     
  Partials       13       13              

Files with missing lines	Coverage Δ
packages/catalog-search/src/CurrentRefinements.jsx	81.08% <100.00%> (+2.13%)	⬆️
packages/catalog-search/src/SearchPagination.jsx	100.00% <ø> (ø)

... and 3 files with indirect coverage changes

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