]]] in a link parameter breaks link syntax

The string ]]] in a link parameter is not properly escaped during XWiki 2.1 syntax rendering.

For example, transforming

[[Link label>>https://www.xwiki.org||data-foo="bar~]~]~]"]]

into XDOM (or annotatedxhtml/1.0) and back gives

[[Link label>>https://www.xwiki.org||data-foo="bar~]]]"]] 

which is not equivalent, as this closes the link in the middle of the parameter. This is because the fix for XRENDERING-459 only adds a single escape character before ]] which is not enough.