Allow us to hide the done button on the KeyboardToolbar

[spaansba]

First of all a big thank you for maintaining this project, the new KeyboardToolbar is exactly what I wanted!!

Describe the solution you'd like
A way to hide the "done" button in the KeyboardToolbar just like we can hide the arrows with the showArrows prop. The perfect solution would be this:

 <KeyboardToolbar
        offset={{ opened: tabBarHeight }}
        showArrows={false}
        showDoneButton={false} // defaults to true like showArrows
 />

Describe alternatives you've considered
I tried setting the dontText to an empty string but it rightfully returns "done"