fix(ios)! remove iPadOS popover code (#941)

- On iPadOS it was possible to configure a popover for setting the position, width and arrow position of the popover.  The code used the deprecated `UIPopoverController`, which would have to be fixed. To keep the plugin also maintainable, this was removed.
- The popover could repositioned with a `CameraPopoverHandle` on a `window.onorientationchange`. This was removed also.
- Removed documentation for popover from `README.md`

www/Camera.js

@@ -22,8 +22,6 @@
 const argscheck = require('cordova/argscheck');
 const exec = require('cordova/exec');
 const Camera = require('./Camera');
-// XXX: commented out
-// CameraPopoverHandle = require('./CameraPopoverHandle');
 
 /**
  * @namespace navigator
@@ -73,7 +71,6 @@ for (const key in Camera) {
  * @property {module:Camera.MediaType} [mediaType=PICTURE] - Set the type of media to select from.  Only works when `PictureSourceType` is `PHOTOLIBRARY` or `SAVEDPHOTOALBUM`.
  * @property {Boolean} [correctOrientation] - Rotate the image to correct for the orientation of the device during capture.
  * @property {Boolean} [saveToPhotoAlbum] - Save the image to the photo album on the device after capture.
- * @property {module:CameraPopoverOptions} [popoverOptions] - iOS-only options that specify popover location in iPad.
  * @property {module:Camera.Direction} [cameraDirection=BACK] - Choose the camera to use (front- or back-facing).
  */
 
@@ -140,7 +137,6 @@ cameraExport.getPicture = function (successCallback, errorCallback, options) {
     const allowEdit = !!options.allowEdit;
     const correctOrientation = !!options.correctOrientation;
     const saveToPhotoAlbum = !!options.saveToPhotoAlbum;
-    const popoverOptions = getValue(options.popoverOptions, null);
     const cameraDirection = getValue(options.cameraDirection, Camera.Direction.BACK);
 
     if (allowEdit) {
@@ -148,11 +144,9 @@ cameraExport.getPicture = function (successCallback, errorCallback, options) {
     }
 
     const args = [quality, destinationType, sourceType, targetWidth, targetHeight, encodingType,
-        mediaType, allowEdit, correctOrientation, saveToPhotoAlbum, popoverOptions, cameraDirection];
+        mediaType, allowEdit, correctOrientation, saveToPhotoAlbum, cameraDirection];
 
     exec(successCallback, errorCallback, 'Camera', 'takePicture', args);
-    // XXX: commented out
-    // return new CameraPopoverHandle();
 };
 
 /**