Document location in create content step 1 must not set a default value

When the manageContent tag does not provide a path where the new document will be created the location field should not be populated with a default value, currently: the site base folder. Users may not notice this and accidently create the new document there. It is very unlikely that that is the correct location.

The document location field must be empty and the user must pick a path manually using a folder picker before the "continue" button becomes available.