EZP-23478: added redirection form fields in content/edit.tpl

Uses a shared content/edit_redirection.tpl, that looks for RedirectURIAfterPublish and RedirectIfDiscarded session variables, and adds input hidden fields with those.
Merge pull request #1118 from ezsystems/EZP-23478-website_toolbar_redirection

EZP-23478: added redirection form fields in content/edit.tpl