message: Teach command palette to fill in selected commandline upon right arrow
  Closes
diff: @@ -244,6 +244,17 @@ namespace winrt::TerminalApp::implementation
  _PreviewActionHandlers(*this, actionPaletteItem.Command());
  }
  }
  + else if (_currentMode == CommandPaletteMode::CommandlineMode)
  + {
  + if (filteredCommand)
  + {
  + SearchBoxPlaceholderText(filteredCommand.Item().Name());
  + }
  + else
  + {
  + SearchBoxPlaceholderText(RS_(L"CmdPalCommandlinePrompt"));
  + }
  + }
  }
  void CommandPalette::_previewKeyDownHandler(IInspectable const& /*sender*/,
  @@ -364,6 +375,17 @@ namespace winrt::TerminalApp::implementation
  _searchBox().PasteFromClipboard();
  e.Handled(true);
  }
  + else if (key == VirtualKey::Right && _currentMode == CommandPaletteMode::CommandlineMode)
  + {
  + if (const auto command{ _filteredActionsView().SelectedItem().try_as<winrt::TerminalApp::FilteredCommand>() })
  + {
  + _searchBox().Text(command.Item().Name());
  + _searchBox().Select(_searchBox().Text().size(), 0);
  + _searchBox().Focus(FocusState::Programmatic);
  + _filteredActionsView().SelectedIndex(-1);
  + e.Handled(true);
  + }
  + }
  }
  // Method Description:
  