Generate an object that maps asset names name to a server-relative urls.
Assets in request and static files are included.

@param {String} target The build target name.

@returns {Object} Map of asset names to urls
function generateStaticUrls( target ) {
	const urls = { ...staticFilesUrls };
	const assets = getAssets( target ).assetsByChunkName;

	forEach( assets, ( asset, name ) => {
		urls[ name ] = asset;
	} );

	return urls;
}