Normalize the white space from the link reference when creating a link to a new page

In Chrome if you follow these steps:

• create a new page
• type "link label " (notice the trailing space at the end)
• Ctrl+A to select all the text
• Create link leaving the defaults
• Save
• Click on the link from view mode to create the new page

The reference of the new page has a non-breaking-space at the end (instead of plain space) which can cause problems. See XWIKI-14854. We should normalize the link label when using it as a new page reference to avoid these problems.