Allow in the create UI/action to specify a different location from an inexistent page

Currently, the create action always determines the spaceReferen and name if the current page does not exist, ignoring any request parameters specifying a different location.

This results in an inconsistent behavior with what happens when you try to create a page from an existing one (i.e. pressing the + Create button) because when the current page does not exist (enforced by the fix for XWIKI-14214), the current user will only be asked to specify the page type, without being able to specify a different location, or even title (now because of XWIKI-14214).

What we need to do is to always prioritize in the create action the request parameters, regardless if the current page exists or not. Only in the case when the parameters are not specified and the current page does not exist, should the create action default to the current page.