[iOS] toolbarposition=top will conflict the upper side of inappbrowser webiew

# Bug Report

## Problem

### What is expected to happen?
When you set the option: `toolbarposition=top` , it should appear in the top of the page and [not covering the upper part of the page].

### What does actually happen?
When you set the option: `toolbarposition=top` , this covering part of the upper side of the web page.
, and also a grey empty solid bar appear at the bottom.


## Information

### Command or Code

`iabRef = cordova.InAppBrowser.open('https://github.com/apache/', '_blank', 'location=no,toolbarposition=top,hidenavigationbuttons=no,usewkwebview=yes');`

### Environment, Platform, Device

iOS 13.2.2, iPhone Xs MAX

### Version information

- Phonegap/Cordova CLI 9.0.0 (ios 5.0.1)
- Cordova-plugin-inappbrowser version: master

## Checklist

- [x] I searched for existing GitHub issues
- [x] I updated all Cordova tooling to most recent version
- [x] I included all the necessary information above

Start by reproducing the Cordova.InAppBrowser.open call with toolbarposition=top and usewkwebview=yes on the reported iOS 13.2.2 environment. Inspect the iOS InAppBrowser toolbar and web-view layout behavior; done means the toolbar does not cover the page and the unwanted grey bar is absent.

Written by the indexing model from the issue text.