Summary:
The showcase is displayed in the homepage as well as in a standalone showcase page. The source data for these two pages is embedded in each page, resulting in repetition of data across both.
This PR splits out all of the showcase data to its own file, which is then loaded into the Metadata component during website generation.
`cd website && npm start`, then verified index and showcase loaded successfully
`cd website && node server/generate.js`, confirmed script runs successfully
Closes https://github.com/facebook/react-native/pull/12626
Differential Revision: D4632036
Pulled By: hramos
fbshipit-source-id: 2d1ad890e78e457205179e36c3ef04ffec354ad9
Hector Ramos