New login screen (#1331)

* wip

* feat: first draft of auth.config

* chore: auth methodS

* chore: styling

* styling, styling, styling

* feat: Auth notices

* chore: Remove server-rendered pages, move shared/components -> components

* lint

* cleanup

* cleanup

* fix: Remove unused component

* fix: Ensure env variables in prod too

* style tweaks

* fix: Entering SSO email into login form fails
fix: Tweak language around guest signin

app/components/BreadcrumbMenu.js

@@ -0,0 +1,25 @@
+// @flow
+import * as React from "react";
+import { Link } from "react-router-dom";
+import { DropdownMenu, DropdownMenuItem } from "components/DropdownMenu";
+
+type Props = {
+  label: React.Node,
+  path: Array<any>,
+};
+
+export default class BreadcrumbMenu extends React.Component<Props> {
+  render() {
+    const { path } = this.props;
+
+    return (
+      <DropdownMenu label={this.props.label} position="center">
+        {path.map(item => (
+          <DropdownMenuItem as={Link} to={item.url} key={item.id}>
+            {item.title}
+          </DropdownMenuItem>
+        ))}
+      </DropdownMenu>
+    );
+  }
+}