Build: Split packages and blocks to their webpack configs.

This also adds support for the viewScript for blocks fixing 
the PDF preview for file blocks.

Props desrosj, gziolo.
See #53397.


git-svn-id: https://develop.svn.wordpress.org/trunk@51259 602fd350-edb4-49c9-b593-d223f7449a82

webpack.config.js

@@ -1,3 +1,4 @@
+const blocksConfig = require( './tools/webpack/blocks' );
 const mediaConfig = require( './tools/webpack/media' );
 const packagesConfig = require( './tools/webpack/packages' );
 
@@ -11,6 +12,7 @@ module.exports = function( env = { environment: "production", watch: false, buil
 	}
 
 	const config = [
+		blocksConfig( env ),
 		mediaConfig( env ),
 		packagesConfig( env ),
 	];