fix: allow Overlay to be focusable in iOS with Full Keyboard Access enabled (react-navigation#12600)

**Motivation**

Currently, if you are using Full Keyboard Access in iOS, there is no way
to close the drawer once it has been opened, as the Pressable within the
Overlay is not focusable.

**Test plan**

in iOS, with Full Keyboard Access enabled at the OS level (System
Settings -> Accessibility -> Keyboards and Typing -> Full Keyboard
Access -> On)

- Open a drawer
- Try to navigate using only the keyboard to the Overlay to close it
- Press space to close the Overlay

Author: ckknight

packages/react-native-drawer-layout/src/views/Overlay.native.tsx

@@ -41,6 +41,7 @@ export function Overlay({
         style={styles.pressable}
         role="button"
         aria-label={accessibilityLabel}
+        accessible
       />
     </Animated.View>
   );