Enhancement: Replace picker to select camera folder with native one

The custom picker to select the camera folder was replaced with the native one. Now, it is ready for
scoped storage and some problems to select a folder in the SD Card were fixed. Also, a new field to show
the last synchronization timestamp was added.

https://github.com/owncloud/android/issues/2899 https://github.com/owncloud/android/pull/3293