Restored selection range is not a correct selection range

[scofalik]

1. Assume an editor with contents <p>[]</p>.
2. Copy & paste two paragraphs into it.
3. Following deltas will be generated: remove old p, insert new p 1, insert new p 2. The remove will be the first one. After it is applied, undo will try to save the batch. Since there is nothing in editor at this point, the selection will be placed at [ 0 ] and it will be saved this way.

Then undo.

1. New paragraphs will be removed.
2. Old paragraph will be recovered.
3. Selection will be restored. It will start from [ 0 ]. After it will be transformed by all deltas, it ends up at [ 1 ]. Which is incorrect selection position: <p></p>[].

In ckeditor/ckeditor5-engine#1138 I introduce DocumentSelection#hasOwnRange to overcome this issue.