Bugfix: Apply text selection range for new files

We've fixed a bug, where the text selection range for a new file has not been applied only for the file name but also
for the file extension.
This is now working as in the rename modal and just selects the text for the file name.

https://github.com/owncloud/web/issues/6756
https://github.com/owncloud/web/pull/6803
