[BUGFIX] URL-encoded title in link wizard

The security fix introduced a bug that the title is encoded
every time the link wizard is opened, leading to multiple
encoded strings.

Solution is to not encode it centrally but encode it just
before using it in the JavaScript context.

Fixes: #41413
Releases: 4.5, 4.7, 6.0, 6.1, 6.2
Change-Id: I6b08db290d5457761edc4506105672d79840764d
Reviewed-on: https://review.typo3.org/27925
Reviewed-by: Markus Klein
Tested-by: Markus Klein