Add transaction card component and provider (#5)

explorer/src/components/NetworkStatusButton.tsx

@@ -0,0 +1,28 @@
+import React from "react";
+import { useNetwork, NetworkStatus } from "../providers/network";
+
+function NetworkStatusButton() {
+  const { status, url } = useNetwork();
+
+  switch (status) {
+    case NetworkStatus.Connected:
+      return <span className="btn btn-white lift">{url}</span>;
+
+    case NetworkStatus.Connecting:
+      return (
+        <span className="btn btn-warning lift">
+          {"Connecting "}
+          <span
+            className="spinner-grow spinner-grow-sm text-dark"
+            role="status"
+            aria-hidden="true"
+          ></span>
+        </span>
+      );
+
+    case NetworkStatus.Failure:
+      return <span className="btn btn-danger lift">Disconnected</span>;
+  }
+}
+
+export default NetworkStatusButton;