Use latest version of binderhub-client

- Also construct URL to binder dynamically, assumed to be under
  /services/binder on the same host
- Use a submodule to bring in latest version of the binderhub-client
  for now, as things move fast. Currently at jupyterhub/binderhub#1742

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "binderhub"]
+	path = binderhub
+	url = https://github.com/yuvipanda/binderhub.git

package.json

@@ -10,7 +10,7 @@
     "watch": "webpack --watch"
   },
   "dependencies": {
-    "@jupyterhub/binderhub-client": "^0.3.0",
+    "@jupyterhub/binderhub-client": "file:binderhub/js/packages/binderhub-client",
     "react": "^18.2.0",
     "react-dom": "^18.2.0",
     "xterm": "^5.1.0"

src/ImageBuilder.jsx

@@ -1,11 +1,14 @@
 
 import { Terminal } from 'xterm';
 import { useEffect, useState } from 'react';
-import BinderImage  from '@jupyterhub/binderhub-client';
+import { BinderRepository }  from '@jupyterhub/binderhub-client';
 
 function buildImage(repo, ref, term) {
     const providerSpec = "gh/" + repo + "/" + ref;
-    const image = new BinderImage(providerSpec, "https://mybinder.org/")
+    // FIXME: Assume the binder api is available in the same hostname, under /services/binder/
+    let binderUrl = new URL(window.location.origin);
+    binderUrl.pathname = '/services/binder/';
+    const image = new BinderRepository(providerSpec, binderUrl.toString(), null, true)
     image.onStateChange('*', (oldState, newState, data) => {
         term.write(data.message);
     })
@@ -59,4 +62,4 @@ export function ImageBuilder() {
 
         </div>
     </div>
-}
+}