Display the keyboard shortcut tip on both "Manage Libraries..."

This commit adds the Menu+Shift+I shortcut to the remaining menu entry in Base.java.

When the shortcut is called, the menu entry from Base.java is the one that will be called.

Author: feikname

Diff for: app/src/processing/app/Base.java

@@ -1070,6 +1070,10 @@ public void rebuildImportMenu(JMenu importMenu) {
     importMenu.removeAll();
 
     JMenuItem menu = new JMenuItem(tr("Manage Libraries..."));
+    // Ctrl+Shift+I on Windows and Linux, Command+Shift+I on macOS
+    menu.setAccelerator(KeyStroke.getKeyStroke('I',
+        Toolkit.getDefaultToolkit().getMenuShortcutKeyMask() |
+        ActionEvent.SHIFT_MASK));
     menu.addActionListener(e -> openLibraryManager("", ""));
     importMenu.add(menu);
     importMenu.addSeparator();