feat(tazjin/nittredir): Add Chrome extension to redirect to Nitter

There is another extension for this already, but it hooks in after the
page has already started loading - doing it on the URL change handler
is much faster.

Change-Id: I442552cbd8bb040df999a1624cafd436f4a7b875
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2430
Reviewed-by: tazjin <mail@tazj.in>
Tested-by: BuildkiteCI

users/tazjin/nittredir/background.js

@@ -0,0 +1,10 @@
+/**
+ * Register a URL change handler that redirects twitter.com links to nitter.net
+ */
+
+chrome.webRequest.onBeforeRequest.addListener(function(details) {
+  let url = new URL(details.url);
+  return {
+    redirectUrl: ('https://nitter.net' + url.pathname)
+  };
+}, {urls: ['*://twitter.com/*'], types: ['main_frame']}, ['blocking']);