cmd/tsconnect: allow SSH username to be specified

Redoes the UI to be a form, with a username field and a host drop-down.

Fixes #5139

Signed-off-by: Mihai Parparita <mihai@tailscale.com>

cmd/tsconnect/index.html

@@ -12,7 +12,27 @@
         <div class="text-gray-600" id="state">Loading…</div>
       </header>
     </div>
-    <div id="peers" class="container mx-auto px-4"></div>
+    <form
+      id="ssh-form"
+      class="container mx-auto px-4 hidden flex justify-center"
+    >
+      <input type="text" class="input username" placeholder="Username" />
+      <div class="select-with-arrow mx-2">
+        <select class="select"></select>
+      </div>
+      <input
+        type="submit"
+        class="button bg-green-500 border-green-500 text-white hover:bg-green-600 hover:border-green-600"
+        value="SSH"
+      />
+    </form>
+    <div id="no-ssh" class="container mx-auto px-4 hidden text-center">
+      None of your machines have
+      <a href="https://tailscale.com/kb/1193/tailscale-ssh/" class="link"
+        >Tailscale SSH</a
+      >
+      enabled. Give it a try!
+    </div>
     <script src="dist/index.js"></script>
   </body>
 </html>