Added server management modal

lib/screens/home/fab.dart

@@ -0,0 +1,25 @@
+import 'package:flutter/material.dart';
+
+import 'package:adguard_home_manager/screens/home/management_modal.dart';
+
+class HomeFab extends StatelessWidget {
+  const HomeFab({Key? key}) : super(key: key);
+
+  @override
+  Widget build(BuildContext context) {
+
+    void openManagementBottomSheet() {
+      showModalBottomSheet(
+        context: context, 
+        isScrollControlled: true,
+        builder: (context) => const ManagementModal(),
+        backgroundColor: Colors.transparent,
+      );
+    }
+
+    return FloatingActionButton(
+      onPressed: openManagementBottomSheet,
+      child: const Icon(Icons.shield_rounded),
+    );
+  }
+}