fix(fireEvent): Make sure react dispatches focus/blur events

[eps1lon]

What:

Fix failing tests for react@experimental

Why:

• see test(fireEvent): Add expected behavior for blur/focus in React #757 for focusin/focusout rationale
• why test react@experimental: In case next is not released alongside experimental (such is the case right now). We don't support any experimental API right now but setting up infra before actual feature work makes feature work more approachable.

How:

• Extend test matrix to react@experimental (in addition to next and latest)
  Switch from REACT_NEXT environment flag to REACT_DIST enum which can hold a valid npm dist tag for react.
• fire focusin alongside focus and focusout alongside blur which is similar to how we handle mouseEnter/mouseLeave.
  Ideally we'd get everybody on board to using .focus() and blur() instead but that would only work with [email protected] or a browser which is less than ideal.
  Checklist:

• [ ] Documentation added to the
  docs site
• Tests
• [ ] Typescript definitions updated
• Ready to be merged
  

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[codecov]

Codecov Report

Merging #758 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master      #758   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         4           
  Lines          101       109    +8     
  Branches        16        16           
=========================================
+ Hits           101       109    +8     

Impacted Files	Coverage Δ
src/fire-event.js	100.00% <100.00%> (ø)

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[kentcdodds]

This is reasonable 👍 thanks!

[kentcdodds]

🎉 This PR is included in version 10.4.8 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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