Popover: Unnecessary re-renders when document clicked

### Description

All Popovers in the page re-render on document clicked, even if none are visible.
Should only render Popovers which are open and have a true state change.

### Reproduce Steps

1. Wrap a button with a Popover
2. In React DevTools enable the **Highlight updates when components render** option.
3. Click anywhere in the page and watch the button be re-rendered, regardles of whether the Popover is visible.
4. For extra proof use the Profiler flamegraph to record this action.

### Error Trace (if possible)

Not error; optimisation.

### Solution

Within document click listener, add early return if `showPopper` is already false in order to prevent setting state to false again.

### Additional Information

ElementReact version: 1.4.34