Export react-dart members and add capturing event handlers

[clairesarsam-wf]

Ultimate problem:

• Using synthetic event classes required importing react:react.dart in addition to over_react:over_react.dart.
• Using setClientConfiguration and ReactElement required importing react:react_client.dart.
• ReactJS supports capturing event handlers (briefly mentioned here) and so does react-dart, but OverReact didn't.

How it was fixed:

• Export synthetic event classes (this doesn't generate any warnings/infos for consumers already importing react:react.dart.
• Export setClientConfiguration and ReactElement.
• Add capturing event handlers to DomPropsMixin.

Testing suggestions:

• Consume this branch in WSD and note no issues occur.

Potential areas of regression:

None.

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FYA: @greglittlefield-wf @aaronlademann-wf @jacehensley-wf @clairesarsam-wf @joelleibow-wf

[aviary-wf]

Raven

Number of Findings: 0

[codecov-io]

Codecov Report

Merging #61 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #61      +/-   ##
==========================================
+ Coverage   97.73%   97.75%   +0.02%     
==========================================
  Files          28       28              
  Lines        1365     1374       +9     
==========================================
+ Hits         1334     1343       +9     
  Misses         31       31

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[aaronlademann-wf]

QA +10

• Testing instruction
• Dev +1's
• Dev/QA +10
• Unit tests created/updated
• All unit tests pass
• Rosie ran/Rosie comment displays expected info
• Dependency Scan Clean

[jacehensley-wf]

+1