Jsx transform

[unional]

PR for issue #3788

--jsx react:

--jsx transform --jsxNamesapce React --jsxComposeFunction createElement --jsxSpreadFunction __spread --jsxChildrenAsArray false

--jsx transfrom:

--jsx transform --jsxNamespace JSX --jsxComposeFunction compose --jsxSpreadFunction spread --jsxChildrenAsArray false

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[msftclas]

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[unional]

This is a more elaborate version of #6146

[RyanCavanaugh]

We're going to go with #6146 (see comments there for rationale)