Implement HostsManager for managing hosts file edits with permission handling

- Added PermissionManager class for managing sudo permissions.
- Introduced HostsManager class for high-level operations on hosts file.
- Implemented methods for entering/exiting edit mode, toggling entries, moving entries, updating entries, saving the hosts file, and restoring backups.
- Integrated permission validation and backup creation during edit operations.
- Enhanced main application to support edit mode and associated actions.
- Added tests for PermissionManager and HostsManager to ensure functionality and error handling.

tests/test_main.py

@@ -376,6 +376,9 @@ class TestHostsManagerApp:
             app = HostsManagerApp()
             app.update_entry_details = Mock()
             
+            # Mock the display_index_to_actual_index method to return the same index
+            app.display_index_to_actual_index = Mock(return_value=2)
+            
             # Create mock event with required parameters
             mock_table = Mock()
             mock_table.id = "entries-table"
@@ -388,6 +391,7 @@ class TestHostsManagerApp:
             # Should update selected index and details
             assert app.selected_entry_index == 2
             app.update_entry_details.assert_called_once()
+            app.display_index_to_actual_index.assert_called_once_with(2)
     
     def test_data_table_header_selected_ip_column(self):
         """Test DataTable header selection for IP column."""