Make IOverflowMenuOptions.title optional

[jtpio]

Right now it looks like it's possible to disable the overflow menu for a menu bar with:

const overflowOptions = {
  overflowMenuOptions: { isVisible: false, title: '' }
};

However title still needs to be provided even if isVisible is set to false.

This change makes title optional so this does not have to be the case anymore:

const overflowOptions = {
  overflowMenuOptions: { isVisible: false }
};

---

overflowMenuOptions.overflowMenuVisible has been renamed overflowMenuOptions.isVisible