Apply patch-package to fix "Premature close" bug

We see that for some fetches of certain lengths after certain amount
of parallelism, we see "Premature close" errors as documented in this
issue: node-fetch/node-fetch#1576

We are applying the suggested fix in this PR:
Treverix/node-fetch@625fd38?diff=split

We do so by using patch-package to path our node-fetch-cjs, an then
inlining a copy of node-fetch-cjs into our built files.

packages/isomorphic-unfetch/.gitignore

@@ -0,0 +1 @@
+dist/

packages/isomorphic-unfetch/index.js

@@ -1,7 +1,5 @@
 function r(m){return m && m.default || m;}
 module.exports = (typeof process == 'undefined'
 		? global.fetch || r(require('unfetch'))
-		: function(url, opts) {
-		  return r(require('node-fetch-cjs'))(String(url).replace(/^\/\//g,'https://'), opts);
-		}
+		: r(require('./dist/server'))
 );