feat: react challenges (#16099)

* chore(packages): Update redux utils

* feat(Panes): Invert control of panes map creation

* feat(Modern): Add view

* feat(Panes): Decouple panes from Challenges

* fix(Challenges): Decouple challenge views from panes map

* fix(Challenge/views): PanesMap => mapStateToPanesMap

This clarifies what these functions are doing

* fix(Challenges): Add view type

* fix(Panes): Remove unneeded panes container

* feat(Panes): Invert control of pane content render

This decouples the Panes from the content they render, allowing for
greater flexibility.

* feat(Modern): Add side panel

This is common between modern and classic

* feat(seed): Array to string file content

* fix(files): Modern files should be polyvinyls

* feat(Modern): Create editors per file

* fix(seed/React): Incorrect keyfile name

* feat(Modern): Highligh jsx correctly

This adds highlighting for jsx. Unfortunately, this disables linting for
non-javascript files as jshint will only work for those

* feat(rechallenge): Add jsx ext to babel transformer

* feat(seed): Normalize challenge files head/tail/content

* refactor(rechallenge/build): Rename function

* fix(code-storage): Pull in files from localStorage

* feat(Modern/React): Add Enzyme to test runner

This enables testing of React challenges

* feat(Modern): Add submission type

* refactor(Panes): Rename panes map update action

gulpfile.js

@@ -108,6 +108,7 @@ const paths = {
     resolve('codemirror', 'lib/codemirror.js', 'addon/lint/lint.js'),
     resolve('codemirror', 'lib/codemirror.js', 'addon/lint/javascript-lint.js'),
     resolve('codemirror', 'lib/codemirror.js', 'mode/javascript/javascript.js'),
+    resolve('codemirror', 'lib/codemirror.js', 'mode/jsx/jsx.js'),
     resolve('codemirror', 'lib/codemirror.js', 'mode/xml/xml.js'),
     resolve('codemirror', 'lib/codemirror.js', 'mode/css/css.js'),
     resolve('codemirror', 'lib/codemirror.js', 'mode/htmlmixed/htmlmixed.js'),